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HighCISA KEVExploited in the wildPublic exploit

Google Chrome Mojo sandbox escape on Windows

IdentifiersCVE-2025-2783CWE-20

CVE-2025-2783 is a high-severity sandbox escape vulnerability in Mojo, Chromium/Chrome’s inter-process communication framework, affecting Google Chrome on Windows prior to 134.0.6998.177. The issue is described as an incorrect handle / incorrect handle handling flaw in Mojo. Supporting content further indicates the bug involved improper validation of pseudo-handles in Chromium IPC, where process pseudo-handles (-1) were validated while thread pseudo-handles (-2) were overlooked in certain circumstances, enabling manipulation through the ipcz/Mojo IPC path. A remote attacker could trigger the flaw using a malicious file, resulting in escape from the Chrome renderer sandbox on Windows. The vulnerability was exploited in the wild as a zero-day, including in Operation ForumTroll and other espionage activity.

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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 attacker to break out of Chrome’s sandbox on Windows. In practical terms, this can enable arbitrary code execution outside the browser sandbox, arbitrary file execution/code injection in the browser process, and compromise of confidentiality, integrity, and availability on the victim system. The flaw was reported as exploited in targeted espionage campaigns and malware delivery operations, including deployment of spyware and backdoors.

Mitigation

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

If immediate patching is not possible, reduce exposure by limiting handling of untrusted files and preventing users from opening attacker-supplied files or attachments in Chrome or Chromium-embedded applications. Apply least-privilege controls to browser execution, consider additional OS-level sandboxing/hardening for embedded Chromium applications where feasible, and monitor for related post-exploitation behaviors noted in reporting, such as COM CLSID hijacking / InProcServer32 registry modifications. These are temporary risk-reduction measures and do not replace patching.

Remediation

Patch, then assume compromise.

Upgrade Google Chrome on Windows to version 134.0.6998.177 or later. For Chromium-derived software, apply the corresponding upstream fix; the provided content also notes CefSharp packages should be upgraded to 134.3.90 or later where applicable. In enterprise environments, verify the patched browser version is deployed across endpoints and ensure browsers are restarted so the update is actually applied.
PUBLIC EXPLOITS

Exploits

2 valid exploits after Mallory filtered fakes, detection scripts, and README-only repos (3 hidden).

VALID 2 / 5 TOTALView more in app
CVE-2025-2783MaturityPoCVerified exploit

Repository contains a real Windows Chromium full-chain exploit for CVE-2025-2783 rather than a detector. Structure is simple: README documents the chain, demo/exp.html provides the browser-side trigger and staging logic, and src/ contains the native payload implemented as a Chromium-linked shared library plus an embedded copy of MinHook for runtime API/function detouring. The BUILD.gn file shows the intended build model: compile main.cc into a shared library named exploit_mojo with dependencies on Chromium ipcz and mojo internals. The main exploit capability is sandbox escape followed by native code execution. According to README and visible code, the DLL initializes from DllMain by spawning a thread, locates chrome.dll, resolves version-specific offsets, and uses MinHook to detour internal Chromium/V8 functionality. One hook targets V8Console::Debug so JavaScript in the demo page can pass an ArrayBuffer containing second-stage shellcode into native code. Another hook targets ipcz relay handling (described as OnAcceptRelayedMessage) to craft a spoofed RelayMessage request and obtain a privileged thread handle from a higher-privileged process. The exploit then performs thread hijacking: suspend thread, alter context, and invoke Windows APIs such as VirtualAlloc, ReadProcessMemory, and CreateThread to stage and run shellcode. The browser-side demo is not just a static page; it contains substantial JavaScript/Wasm exploit logic and explicitly fetches windows/shellcode.bin, computes addresses, writes staged code into RWX memory, and signals the native hook path via console.debug. README states the demo should be served locally with python -m http.server and opened at http://127.0.0.1:8000/exp.html. This makes the attack chain a combination of web/browser delivery and local/native post-exploitation on Windows. Notable fingerprintable artifacts include the local demo URL, the fetched shellcode path windows/shellcode.bin, references to payload.bin and shellcode.bin, the target module chrome.dll, and hardcoded supported Chrome versions in g_node_offset_map. The repository is operational but not broadly weaponized: it includes a working payload path and shellcode execution flow, yet relies on hardcoded offsets, Chromium source-tree integration, and a narrow Windows/Chrome compatibility window.

aronfourDisclosed Apr 1, 2026markdownhtmlbrowserlocalweb
ChromSploit-FrameworkMaturityPoCFrameworkChromSploit FrameworkVerified exploit

ChromSploit Framework is a modular, extensible exploitation and research platform focused on browser and server vulnerabilities. It provides operational exploit modules for several high-profile CVEs (including Chrome, Edge, Firefox, Tomcat, and Git), with a strong emphasis on safety: all exploits default to simulation mode, and real exploitation requires explicit authorization. The framework supports multi-stage browser exploit chains, advanced payload obfuscation, automated tunneling (ngrok), and C2 integration (Sliver, Metasploit). It includes a professional reporting system, live monitoring, and evidence collection. The repository is well-structured, with clear separation between core logic, modules, exploits, and documentation. Numerous endpoints are fingerprintable, including local HTTP servers for exploit delivery, OAuth phishing, and data exfiltration. The codebase is primarily Python, with supporting JavaScript, JSP, and shell scripts. This framework is suitable for advanced security research, red teaming, and educational demonstrations, but should only be used in authorized, isolated environments due to the presence of real exploit code (even though simulation is the default).

Leviticus-TriageDisclosed May 26, 2025pythonjavascriptbrowsernetworklocal
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
CefsharpCefsharp.Offscreenapplication
CefsharpCefsharp.Offscreen.Netcoreapplication
CefsharpCefsharp.Winformsapplication
CefsharpCefsharp.Winforms.Netcoreapplication
CefsharpCefsharp.Wpfapplication
CefsharpCefsharp.Wpf.Hwndhostapplication
CefsharpCefsharp.Wpf.Netcoreapplication
GoogleChromeapplication

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

What this page doesn’t show

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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.
Exposure mapping

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Threat actor evidence5

Every observed campaign linking this CVE to a named adversary.

Associated malware11

Malware families riding this exploit, with evidence and IOCs.

Detection signatures2

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 activity72

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