Remote Code Execution in GitHub Enterprise Server via crafted git push options
CVE-2026-3854 is a high-severity remote code execution vulnerability in GitHub Enterprise Server (and, per supporting reporting, related GitHub cloud offerings) caused by improper neutralization of special elements in user-supplied git push option values. During a git push, attacker-controlled push option values were incorporated into internal service headers / metadata without sufficient sanitization. Because the internal header format used a delimiter character that could also appear in user input, a user with push access could craft push option values that injected additional trusted metadata fields into downstream services. Supporting reporting describes this as a command-injection-style flaw in GitHub’s git infrastructure that could manipulate the execution environment for push processing, bypass sandboxing protections, and ultimately execute arbitrary commands on the server handling the push.
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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.
Mitigation
If you can’t patch tonight, do this now.
Remediation
Patch, then assume compromise.
Exploits
1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos (6 hidden).
Small 3-file repository containing a README, license, and a single Python script (exploi-git.py). The Python file is the sole code artifact and entry point. It is a self-contained educational proof-of-concept for CVE-2026-3854, modeling GitHub's vulnerable X-Stat header construction/parsing logic entirely in memory. The script defines baseline X-Stat fields, a vulnerable header builder that concatenates push options with semicolons, a parser that honors the last occurrence of duplicate keys, and a patched sanitizer that percent-encodes semicolons. It then runs three demos: (1) basic injection overriding rails_env from production to staging, (2) a conceptual multi-step RCE chain that changes rails_env, custom_hooks_dir, repo_pre_receive_hooks, and enterprise_mode to show how unsandboxed hook execution could occur, and (3) patched behavior showing the injection is neutralized. It also prints a conceptual git push command and external references. No live exploitation occurs: there are no network connections, no subprocess execution, and no file writes. The exploit capability is therefore demonstrative rather than operational, but it clearly documents the attack path and the critical fields/paths involved.
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.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
240 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A high-severity remote code execution vulnerability in GitHub Enterprise products caused by improper sanitization of user-supplied git push option values, enabling command injection and arbitrary command execution on vulnerable systems.
A remote code execution vulnerability in GitHub’s handling of user-supplied git push options, caused by improper sanitization that enabled command/header injection and sandbox bypass.
A critical remote code execution vulnerability in GitHub's handling of user-supplied options during git push operations, allowing attackers with push access to inject trusted metadata fields, bypass sandboxing, execute arbitrary code, and gain read/write access to private repositories or fully compromise vulnerable GitHub Enterprise Server instances.
A high-severity vulnerability in GitHub's git infrastructure caused by internal services blindly trusting user-supplied push option input, enabling attackers to inject trusted internal metadata and gain full read/write access to private GitHub repositories.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.