CriticalPublic exploitVulnerability

CVE-2026-33439

Pre-authentication Java deserialization RCE in OpenIdentityPlatform OpenAM

Published Apr 7, 2026 · Updated 5 days ago

Trending this weekNot trendingOutside this week’s top 100

Mention activity · 30 daysNo mention activity in the last 30 days.

CVSS9.3Critical · v4

EPSS9.3%95th percentile

CISA KEVNoNot listed

In the wildNonePublic exploit, no exploitation reported

Vendor: Open Identity Platform

IdentifiersCVE-2026-33439CWE-502 · Deserialization of Untrusted Data

CVE-2026-33439 is an unsafe Java deserialization vulnerability in OpenIdentityPlatform OpenAM versions prior to 16.0.6. The ClientSession constructor accepts the attacker-controlled jato.clientSession HTTP parameter, which is decoded and passed through Encoder.deserialize() to ApplicationObjectInputStream.readObject() without class filtering. Deserialization occurs during JSP rendering when a JATO ViewBean page contains a jato:form tag, including unauthenticated password-reset pages. This separate deserialization path was not covered by the WhitelistObjectInputStream protection applied to jato.pageSession after CVE-2021-35464. A crafted serialized object supplied through a GET or POST request can execute arbitrary code without authentication.

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Analyst brief

Impact, mitigation & remediation

What it means and what to do now: patch path, interim mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

An unauthenticated remote attacker can execute arbitrary commands with the privileges of the OpenAM server process, compromising the confidentiality, integrity, and availability of the affected server. Successful exploitation can permit access to data available to that process, modification of application data or functionality, and service disruption. Elevated operating-system privileges are not established by the vulnerability itself.

Mitigation

If you can’t patch tonight, do this now.

Until an upgrade is possible, restrict untrusted network access to affected JATO ViewBean endpoints, particularly unauthenticated password-reset pages. Consider blocking requests containing jato.clientSession at an upstream proxy or application firewall, covering both GET query parameters and POST parameters and accounting for request encoding. These exposure-reduction measures are not substitutes for the fixed release.

Remediation

Patch, then assume compromise.

Upgrade OpenIdentityPlatform OpenAM to version 16.0.6 or a later fixed release. Version 16.0.6 routes Encoder.deserialize() through IOUtils.deserialise(), applying the existing WhitelistObjectInputStream class restrictions to jato.clientSession as well as jato.pageSession.

Public exploits

Exploits

9 exploits validated by Mallory's analysis. Hidden: 1 rejected by Mallory's analysis as not a working exploit.

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CVE-2026-33439-PoCThis repository contains a working exploit for CVE-2026-33439, a pre-authentication Java deserialization RCE in ForgeRock/OpenIdentityPlatform OpenAM. The repo includes both a Nuclei template (CVE-2026-33439.yaml) and a standalone Java PoC source/build setup. Because it is part of a framework, the main exploit file is the Nuclei template, which sends unauthenticated GET requests to OpenAM password-reset UI endpoints with a malicious jato.clientSession parameter and a cmd header. The template uses clusterbomb combinations of base paths (sso, openam, auth, opensso, am) and pages (PWResetUserValidation, PWResetQuestion, PWResetSuccess), executes 'cat /etc/passwd', and confirms exploitation by matching root account output in a 200 response. The accompanying Java PoC shows the exploit structure in detail: it generates a reusable serialized PriorityQueue payload using an Apache Click + Xalan TemplatesImpl gadget chain, encodes it in OpenAM-compatible Base64, and optionally sends it with curl. The embedded translet accesses com.iplanet.jato.RequestManager.getRequestContext(), reads the cmd HTTP header, executes /bin/sh -c <cmd>, and writes command output directly to the HTTP response stream, providing in-band echo-based RCE without DNS/OOB channels. The PoC defaults to proxying through http://127.0.0.1:8080 and supports a --no-proxy option. Repository structure is small and focused: one Nuclei template, one Java source file, a manifest, a build script, and a README. Overall purpose: provide both automated scanning/verification and a standalone exploit implementation for unauthenticated OpenAM RCE via jato.clientSession deserialization.Ibonok · Disclosed Apr 28, 2026 · Framework: nuclei · yaml · java · web · networkWeaponized CVE-2026-33439This repository is a compact exploit project for CVE-2026-33439, an unauthenticated Java deserialization RCE in OpenIdentityPlatform OpenAM. It contains 5 files: a Python exploit, a Docker Compose lab for reproducing the issue, a README with vulnerability and usage documentation, plus license and gitignore files. The main exploit file is 02 Exploit/Exploit_CVE_2026_33439.py, which is a standalone Python script rather than a framework module. The exploit’s workflow is: (1) probe likely JATO ViewBean endpoints (/ui/PWResetUserValidation, /ui/PWResetQuestion, /ui/Login), (2) generate and compile a malicious Java EvilTranslet class using attacker-supplied command text, (3) assemble a TemplatesImpl-based serialized gadget chain using OpenAM-bundled libraries, and (4) deliver the serialized payload in the jato.clientSession parameter via HTTP GET or POST to a reachable endpoint. The payload executes arbitrary OS commands through Runtime.getRuntime().exec(), enabling simple command execution, HTTP callback beacons, or reverse shells. The repository also includes 01 Vulnerable/docker-compose.yml, which provisions a vulnerable OpenAM 16.0.5 lab on Tomcat and a separate attacker container. This lab file is not the exploit itself but supports reproduction and testing. The README confirms the target scope as OpenAM versions before 16.0.6 and explains the root cause: jato.clientSession is deserialized without the whitelist protections previously added for jato.pageSession. Overall, this is a real operational exploit PoC with a functional payload path, not merely a detector or write-up. It is operational rather than weaponized because the payload is customizable only through a supplied command string and requires local preparation of specific JAR dependencies.TheMalwareGuardian · Disclosed Apr 30, 2026 · python · yaml · network · webOperational CVE-2026-33439-Python-PoCThis is a small standalone repository consisting of a usage README and one Python 3 exploit script. exploit.py implements a network-based proof of concept for CVE-2026-33439 affecting OpenAM's pre-authentication handling of the jato.clientSession parameter. It contains an embedded compressed Java serialization payload, verifies its SHA-256 digest and Java stream magic bytes after decoding, then appends the resulting URL-safe Base64 value to a user-provided OpenAM URL. A GET request carries the desired shell command in the cmd header; the stated Click/Xalan gadget executes it and reflects stdout/stderr in the response. The script supports configurable timeout, optional HTTP proxying, and opt-in TLS certificate validation. It validates the supplied URL and rejects CR/LF in commands, but otherwise permits arbitrary single-line shell commands. No external Python dependencies, Java runtime, or JAR files are required on the attack host.infernosalex · Disclosed Sep 12, 2026 · python · markdown · network · webOperational CVE-2026-33439-PoCThis six-file Python repository implements an operational exploit for the claimed CVE-2026-33439 unsafe Java deserialization issue in OpenIdentityPlatform OpenAM. build.py downloads Maven dependencies, compiles embedded Java sources, constructs a PriorityQueue → Apache Click → Xalan TemplatesImpl gadget chain, and saves it as payload.b64. exploit.py transmits that payload as the jato.clientSession GET query parameter or POST form parameter to pre-authentication JATO endpoints, with endpoint probing, delivery to all known endpoints, optional proxying, optional TLS validation, and an interactive command loop. The generated interactive translet executes attacker-provided cmd header values through /bin/sh and returns output in the HTTP response; blind mode embeds a command at build time for out-of-band execution. verify.py is a local payload-inspection utility that validates Java serialization magic, extracts strings, checks expected gadget-related classes, and scans for selected callback/classloading indicators. No opaque binary payload is committed; the Java payload source is embedded in build.py.JonasChen0103 · Disclosed Sep 19, 2026 · python · java · web · networkOperational CVE-2026-33439-PocThis two-file repository contains a standalone Python 3 exploit and a short usage README for CVE-2026-33439. CVE-2026-33439.py embeds a serialized Java gadget chain based on PriorityQueue, OpenAM Apache Click Column comparator behavior, and Xalan TemplatesImpl. It patches an EvilTranslet command slot at runtime, URL-safe-Base64 encodes the serialized object, then submits it as the jato.clientSession parameter. The tool automatically probes three OpenAM UI/JATO paths, selects the first reachable endpoint, and delivers the payload via GET by default or POST when requested. It also supports endpoint override, verbose logging, and payload-only output. The README identifies OpenAM versions through 16.0.5 as affected and 16.0.6 as fixed. Execution is blind, but the request remains open until the launched process exits, allowing timing-based confirmation.rh33t · Disclosed Sep 20, 2026 · python · markdown · webOperational openam-cleanThe repository is a standalone command-execution exploit implementation claiming to target CVE-2026-33439 in OpenAM. It contains four files: README.md documents the mechanism and usage; exploit.py builds and delivers the payload; setup.sh downloads dependencies and compiles the builder; and src/PayloadBuilder.java constructs the gadget and generates its Java translet from readable source. There is no exploit-framework integration or opaque embedded serialized blob. PayloadBuilder compiles EvilTranslet to Java 8 bytecode, places it in external Apache Xalan TemplatesImpl, and uses an Apache Click ColumnComparator configured for outputProperties inside a PriorityQueue. It populates queue internals reflectively rather than adding elements through the armed comparator, avoiding premature local gadget activation. It checks the class-file magic/version and Java serialization magic before emitting unpadded Base64URL. An optional compatibility mode prepends a zero byte before encoding. The Python driver sends the payload in the jato.clientSession GET parameter and places the selected command in the cmd header. The translet accesses JATO's current request and response, runs /bin/sh -c, merges stdout/stderr, and attempts to write the output back to the response. The driver supports an alternate endpoint, explicit proxy, timeout, and payload-only output. TLS certificate validation is disabled by default and enabled with --verify-tls. It prints HTTP status and response data even for HTTP error responses, but does not independently verify exploitation success. Its distinctive User-Agent is OpenAM-cleanroom-CVE-2026-33439/1.0. Static inspection shows a coherent exploit attempt rather than a detection-only script, and no obvious fake-exploit behavior or unrelated malicious callbacks. However, execution was not tested, the claimed CVE association and affected OpenAM versions are not independently established by the supplied files, and compatibility depends on the target's deserialization behavior, available classes, JVM restrictions, and response state. Dependency versions describe the local build inputs, not confirmed vulnerable OpenAM releases. The setup script prints SHA-256 hashes but does not compare them against trusted expected values, and it reuses existing JARs without validation. Repository URL, git reference, archive path, and archive size were not supplied; empty metadata and a zero archive-size placeholder reflect that absence. Listed file sizes total 15,465 bytes.amis13 · Disclosed Oct 7, 2026 · python · bash · web · networkOperational CVE-2026-33439This standalone repository implements an intended exploit for CVE-2026-33439: unsafe deserialization of the JATO jato.clientSession parameter in OpenIdentityPlatform OpenAM. Documentation attributes the flaw to an incomplete earlier fix for CVE-2021-35464 and states that OpenAM 16.0.6 fixes it; these claims were not independently verified. The eight files comprise two Python tools, one Bash environment checker, a Docker Compose lab, two Markdown documents, a license, and ignore rules. exploit/build.py embeds Java sources, downloads Apache Click 2.3.0, compiles a translet and payload builder, and generates serialized payload data. exploit/send_payload.py submits unpadded Base64URL payloads to four JATO paths, trying GET first and POST if no successful response contains jato.pageSession. TLS certificate verification is disabled. setup.sh checks prerequisites; it does not install them. The lab pins OpenAM 16.0.5. The intended chain is PriorityQueue deserialization to Click ColumnComparator property resolution to TemplatesImpl translet execution. The visible translet supports command selection through the cmd header, defaults to id, and attempts response-based output with a temporary-file fallback. No reverse shell, persistence mechanism, or external exfiltration destination is implemented in the visible default payload. Printed references to listeners on ports 4444 and 8001 are guidance only, not actual connections. There are significant reliability caveats. The supplied build.py content is truncated, preventing full inspection of comparator construction and serialization. Documentation describes external Xalan classes, but visible code uses JDK-internal Xalan classes, introducing module-access and target-compatibility concerns. Tomcat thread-local availability is conditional; without the request object, custom header commands are unavailable and id is used. The sender expects payload.b64.txt rather than payload.b64, sends no cmd header, and does not display successful response bodies. Its JATO marker detects page behavior, not exploitation. The builder also prints a command referring to an absent exploit.py file. These inconsistencies do not establish that the repository is fake, but operational success remains unverified. Repository URL, git reference, archive location, and archive byte size were not provided; empty strings and zero represent unavailable repository metadata.TeoVMP · Disclosed Oct 29, 2026 · python · java · webOperational CVE-2026-33439_pocThe repository contains three files: a Python exploit client, a README describing the claimed CVE and usage, and a .gitignore excluding Python cache directories. openam_check.py is a standalone command-line exploitation tool, despite calling itself a checker: it accepts a target URL and arbitrary command, embeds a Java deserialization payload, and attempts to print server-side command output. The documented entry points are the OpenAM password-reset UI endpoints, with jato.clientSession identified as the deserialization input. Visible payload content supports a PriorityQueue/OpenAM Click comparator chain leading to Xalan TemplatesImpl and embedded Java command-execution bytecode that reads a cmd request header and launches /bin/sh. The visible response handling tolerates HTTP errors and incomplete reads, attempts subsequent endpoints after failures, and rejects empty or HTML-looking responses as unsuccessful. This output heuristic is not definitive proof of execution. The README states that TLS certificate verification is disabled. No fixed external callback or exfiltration destination is visible. The source is truncated across part of the payload and request-building logic, so exact serialization validity, HTTP request construction, endpoint sequencing, and exploit reliability cannot be fully assessed. CVE-2026-33439 is asserted by the repository, but its attribution and affected versions are not independently established here. Repository URL, revision, and archive size were not supplied; empty strings and zero represent unavailable metadata.stapat1245 · Disclosed Nov 2, 2026 · python · web · networkOperational CVE-2026-33439-PoCThe repository contains three Python utilities, embedded Java payload source, a README, a Hippocratic License, and a .gitignore. It implements a standalone exploitation workflow for the claimed CVE-2026-33439 in OpenIdentityPlatform OpenAM <=16.0.5, rather than merely documenting or detecting the issue. build.py declares six Maven dependencies and compiles Java code to produce a URL-safe Base64 serialization artifact. The described chain connects PriorityQueue and Apache Click property evaluation to Xalan TemplatesImpl and an EvilTranslet. The visible default translet obtains JATO request/response objects through the thread context classloader, executes the cmd header through /bin/sh, and returns combined process output. A second build mode embeds a command for blind execution. The supplied build.py excerpt is truncated, including the gadget-builder implementation and part of the embedded-command template, so the complete chain cannot be independently reviewed from this material. exploit.py delivers payload.b64 using GET or form-encoded POST, supports arbitrary supplied URLs, three predefined JATO routes, optional proxying, configurable timeouts, and interactive command execution. TLS certificate verification is disabled by default. Its interactive interface starts a fresh remote process for each command and simulates persistent directories by prefixing later commands. The --probe operation actually sends an execution payload with 'id'; it is not passive detection. It marks any HTTP 200 response as vulnerable without checking command output, allowing false positives. verify.py decodes the artifact, reports its SHA-256, checks Java serialization magic bytes, searches printable strings for expected classes and suspicious network/loading terms, and offers strings, hex, and binary-export modes. These are heuristic inspection checks, not proof of payload safety, exploitability, or absence of callbacks. The visible code contains no fixed exfiltration or reverse-shell destination. Maven URLs are build-time dependency sources; advisory URLs in the documentation are references, not exploit traffic. The code appears consistent with a real command-execution exploit, with no evident fake-exploit behavior in the supplied excerpts. Exploitation, the CVE attribution, and the affected-version claim were not independently validated. The original repository URL, git reference, and archive size were not supplied; empty strings and zero represent unavailable metadata.duohnson · Disclosed Nov 6, 2026 · python · java · webOperational

Exposure surface

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

Open Identity PlatformOpenamapplication

External references

References

MITRE CVEcve.org · CVE-2026-33439 NVDnvd.nist.gov/vuln/detail/CVE-2026-33439 MITRE CWE · CWE-502Deserialization of Untrusted Data Vendor Advisorygithub.com/OpenIdentityPlatform/OpenAM/security/advisories/GHSA-2cqq-rpvq-g5qj

Activity feed

Recent activity

15 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

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metasploit pull requestsNews · Sep 20, 2026Add OpenAM Deserialization RCE Module (CVE-2026-33439) by LegitCodeRed · Pull Request #21925 · rapid7/metasploit-frameworkAn unauthenticated Java deserialization remote-code-execution vulnerability in OpenIdentityPlatform OpenAM (<= 16.0.5). An attacker can submit a crafted jato.clientSession value to an exposed JATO ViewBean endpoint, such as the password-reset validation endpoint, to execute arbitrary operating-system commands.Read more ↗nuclei templates pull requestsNews · Apr 14, 2026CVE-2026-33439 - OpenAM <= 16.0.5 - Pre-Auth RCE via jato.clientSession Deserialization by DhiyaneshGeek · Pull Request #15905 · projectdiscovery/nuclei-templates · GitHubA pre-authentication remote code execution vulnerability affecting OpenAM versions 16.0.5 and earlier.Read more ↗cvefeed high severityNews · Apr 7, 2026CVE-2026-33439 - Pre-Authentication Remote Code Execution via `jato.clientSession` Deserialization in OpenAMA pre-authentication remote code execution vulnerability in OpenIdentityPlatform OpenAM caused by unsafe Java deserialization of the jato.clientSession HTTP parameter, allowing unauthenticated arbitrary command execution.Read more ↗hacktron blogNews · Apr 7, 2026Pre-Auth RCE in OpenAM via jato.clientSession (CVE-2026-33439) | Hacktron AIA critical pre-authentication remote code execution vulnerability in OpenIdentityPlatform OpenAM caused by unsafe Java deserialization of the jato.clientSession parameter through an unfiltered deserialization path.Read more ↗

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Exposure mappingQuery your assets running an affected version, and investigate the blast radius.

Threat actor evidenceEvery report linking this CVE to a named adversary.

Associated malware1Malware families linked to this CVE, with evidence and IOCs.

Detection signaturesYARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mappingCross-references every affected SKU, including bundled OEM variants.

Social activity9Community discussion across Reddit, Mastodon, and other social sources.