V5: go-git: Malicious reference names may modify files outside the reference storage (CVE-2026-71557)
A path traversal vulnerability in go-git allows malicious reference names to access files outside the intended reference storage in filesystem-backed repositories. This occurs because reference names were used as filesystem paths without proper validation, enabling crafted names like refs/heads/../../config to escape the .git directory. The issue affects applications using the storage/filesystem package and dotgit reference storage, but not those using in-memory storage. A fix is available that validates and rejects unsafe reference names. Users should upgrade to a patched version and avoid untrusted Git servers until patched.
AI Analysis
Technical Summary
The go-git library contains a path traversal vulnerability (CVE-2026-71557) in its handling of reference names when using filesystem-backed storage. Reference names were used directly as filesystem paths without verifying that the resolved path remained within the .git reference storage directory. Malicious reference names such as refs/heads/../../config could cause the library to access or modify files outside the intended storage, including critical repository metadata files like .git/config or .git/HEAD. This vulnerability can be triggered when interacting with a malicious Git server that advertises crafted reference names. The flaw does not affect in-memory storage implementations. The issue has been fixed by adding validation at dotgit storage entry points to reject reference names that resolve outside the reference storage. Users of filesystem-backed storage should upgrade to a fixed version to mitigate this risk.
Potential Impact
An attacker controlling a Git server or reference names can cause a client using go-git with filesystem-backed storage to access or modify files outside the repository's reference storage. This can lead to unauthorized modification of repository metadata files, potentially impacting repository integrity. The vulnerability does not affect confidentiality but impacts integrity and availability to a limited extent. Exploitation requires interaction with a malicious Git server or processing attacker-controlled reference names. The CVSS 3.1 score is 6.3 (medium severity), reflecting network attack vector, low complexity, low privileges required, and user interaction needed.
Mitigation Recommendations
A patch is available that validates reference names at the dotgit storage entry points and rejects those that could escape the reference storage directory. Users of filesystem-backed storage should upgrade to a patched version of go-git (versions >=5.19.2 and excluding 6.0.0-alpha.5). Applications using only in-memory storage are not affected and require no action. Until upgrading, avoid cloning or fetching from untrusted Git servers. Application-level validation of reference names can be a temporary mitigation but does not replace upgrading to a fixed version.
V5: go-git: Malicious reference names may modify files outside the reference storage (CVE-2026-71557)
Description
A path traversal vulnerability in go-git allows malicious reference names to access files outside the intended reference storage in filesystem-backed repositories. This occurs because reference names were used as filesystem paths without proper validation, enabling crafted names like refs/heads/../../config to escape the .git directory. The issue affects applications using the storage/filesystem package and dotgit reference storage, but not those using in-memory storage. A fix is available that validates and rejects unsafe reference names. Users should upgrade to a patched version and avoid untrusted Git servers until patched.
CVSS v3.1
Score 6.3medium
Affected software
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Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The go-git library contains a path traversal vulnerability (CVE-2026-71557) in its handling of reference names when using filesystem-backed storage. Reference names were used directly as filesystem paths without verifying that the resolved path remained within the .git reference storage directory. Malicious reference names such as refs/heads/../../config could cause the library to access or modify files outside the intended storage, including critical repository metadata files like .git/config or .git/HEAD. This vulnerability can be triggered when interacting with a malicious Git server that advertises crafted reference names. The flaw does not affect in-memory storage implementations. The issue has been fixed by adding validation at dotgit storage entry points to reject reference names that resolve outside the reference storage. Users of filesystem-backed storage should upgrade to a fixed version to mitigate this risk.
Potential Impact
An attacker controlling a Git server or reference names can cause a client using go-git with filesystem-backed storage to access or modify files outside the repository's reference storage. This can lead to unauthorized modification of repository metadata files, potentially impacting repository integrity. The vulnerability does not affect confidentiality but impacts integrity and availability to a limited extent. Exploitation requires interaction with a malicious Git server or processing attacker-controlled reference names. The CVSS 3.1 score is 6.3 (medium severity), reflecting network attack vector, low complexity, low privileges required, and user interaction needed.
Mitigation Recommendations
A patch is available that validates reference names at the dotgit storage entry points and rejects those that could escape the reference storage directory. Users of filesystem-backed storage should upgrade to a patched version of go-git (versions >=5.19.2 and excluding 6.0.0-alpha.5). Applications using only in-memory storage are not affected and require no action. Until upgrading, avoid cloning or fetching from untrusted Git servers. Application-level validation of reference names can be a temporary mitigation but does not replace upgrading to a fixed version.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-qgq7-7hm3-q39j
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-71557"]
- Ecosystems
- ["Go"]
- Database Specific Severity
- MODERATE
- Cvss Version
- 3.1
Threat ID: 6a77432dbf8831d539b461e0
Added to database: 08/08/2026, 14:54:37 UTC
Last enriched: 08/08/2026, 15:40:06 UTC
Last updated: 08/09/2026, 00:49:47 UTC
Views: 7
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