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HighPublic exploit

Unauthenticated SSRF in Postiz /public/stream

IdentifiersCVE-2026-34577CWE-918· Server-Side Request Forgery (SSRF)

CVE-2026-34577 is a server-side request forgery vulnerability in Postiz, an AI social media scheduling tool, affecting versions prior to 2.21.3. The issue exists in the GET /public/stream endpoint in PublicController, which accepts a user-controlled url query parameter and proxies the full HTTP response back to the requester. The endpoint performs only a naive validation that the supplied URL ends with 'mp4'; this check can be trivially bypassed by appending .mp4 in a query parameter value or URL fragment. Because the endpoint requires no authentication and lacks SSRF protections, an attacker can cause the Postiz server to issue requests to arbitrary internal or otherwise unreachable resources and return the responses to the attacker.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

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

Successful exploitation allows an unauthenticated remote attacker to read responses from internal services, cloud metadata endpoints, and other network-internal resources reachable from the Postiz server. This can expose sensitive configuration data, credentials, tokens, service metadata, and other internal information. The provided context indicates high confidentiality impact, with no specific integrity or availability impact described.

Mitigation

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

If immediate patching is not possible, restrict or disable access to the vulnerable GET /public/stream endpoint, especially from untrusted networks. Apply outbound network egress filtering from the Postiz host/container to block access to internal address space and cloud metadata services, and enforce network-layer controls preventing the application from reaching sensitive internal resources. Monitoring for suspicious requests through /public/stream with attacker-controlled url values may help detect exploitation attempts.

Remediation

Patch, then assume compromise.

Upgrade Postiz to version 2.21.3 or later, which patches this issue. The vulnerable behavior in the /public/stream endpoint should be removed or constrained with robust SSRF defenses, including strict allowlisting of permitted destinations and safe URL parsing/validation rather than suffix-based checks.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

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
GitroomPostizapplication

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

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

6 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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Exposure mapping

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

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

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

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity5

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-34577
NVD
nvd.nist.gov/vuln/detail/CVE-2026-34577
MITRE CWE · CWE-918
Server-Side Request Forgery (SSRF)
Vendor Advisory
github.com/gitroomhq/postiz-app/security/advisories/GHSA-mv6h-v3jg-g539
Release Notes
github.com/gitroomhq/postiz-app/releases/tag/v2.21.3