Enterprise ServerApplication · GitHub
CVE-2026-17556
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA path traversal vulnerability was identified in GitHub Enterprise Server that allowed an unauthenticated attacker to delete arbitrary files and directories on the instance, including the entire user storage directory containing Git LFS objects, release assets, attachments, and avatars. The X-GitHub-Request-Id request header was used without sanitization as a filesystem path segment for the upload buffer directory, so a traversal value pointed the buffer at an arbitrary path and the deferred cleanup routine recursively removed the traversed target. Exploitation required only network reachability to the instance and no authentication, and it worked even when private mode was enabled. This vulnerability affected all versions of GitHub Enterprise Server prior to 3.22 and was fixed in versions 3.21.4, 3.20.6, 3.19.10, 3.18.13 and 3.17.19. This vulnerability was reported via the GitHub Bug Bounty program.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidencePath traversal vulnerability in GitHub Enterprise Server where the X-GitHub-Request-Id HTTP header is used without sanitization as a filesystem path segment for an upload buffer directory. Attackers can inject traversal sequences to point the buffer to arbitrary paths, and a deferred cleanup routine recursively deletes the traversed target, allowing unauthenticated deletion of any files including the entire user storage directory containing Git LFS objects, release assets, attachments, and avatars.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Enterprise ServerApplication
< 3.17.19>= 3.18.0, < 3.18.13>= 3.19.0, < 3.19.10>= 3.20.0, < 3.20.6>= 3.21.0, < 3.21.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Check GitHub Enterprise Server versionRun 'ghe-version' command or check the management console's version display. Compare the installed version against the affected ranges: < 3.17.19, >= 3.18.0 and < 3.18.13, >= 3.19.0 and < 3.19.10, >= 3.20.0 and < 3.20.6, >= 3.21.0 and < 3.21.4Affected if The installed version falls within any of the affected ranges listed above
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Review HTTP access logs for malicious headersSearch web server or load balancer logs for requests containing X-GitHub-Request-Id headers with traversal sequences. Look for patterns like '../' or '..\' in the header valueAffected if Any X-GitHub-Request-Id header values contain directory traversal sequences (e.g., ../../)
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Check for unexpected file or directory deletionsAudit storage filesystem for missing files or directories, particularly in user storage areas containing Git LFS objects, release assets, attachments, and avatars. Compare current state against known-good backups or monitoring baselinesAffected if Files or directories in storage locations have been deleted without corresponding legitimate administrative action
If the installed version is within any of the affected ranges, or if logs show traversal sequences in X-GitHub-Request-Id headers, or if unexpected deletions exist in storage areas, the environment is affected by this vulnerability.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.17.193.18.133.19.10
Upgrade GitHub Enterprise Server to version 3.21.4, 3.20.6, 3.19.10, 3.18.13, 3.17.19 or later. For systems that cannot immediately upgrade, consider network-level restrictions to limit exposure, though the definitive fix is the version upgrade.
GitHub Enterprise Server 3.22 or later (specifically 3.21.4, 3.20.6, 3.19.10, 3.18.13, or 3.17.19 minimum)
- 1. Identify current GitHub Enterprise Server version by checking the administrative management console or running 'ghe-version' command
- 2. Verify the version is one of the affected versions prior to 3.22, or specifically 3.21.x before 3.21.4, 3.20.x before 3.20.6, 3.19.x before 3.19.10, 3.18.x before 3.18.13, or 3.17.x before 3.17.19
- 3. Plan an upgrade to GitHub Enterprise Server 3.22 or later (recommended)
- 4. Follow GitHub's standard upgrade procedure: backup the instance, download the target release from GitHub Enterprise downloads, and run the upgrade using 'ghe-upgrade' command
- 5. After upgrade, verify the X-GitHub-Request-Id header is now properly sanitized before use as a filesystem path segment
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Enterprise Server
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-17556 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-17556 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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