gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

5.3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N

EPSS

• CVE-2026-44309: 0.14% estimated exploitation activity in the next 30 days; percentile 3.34 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary gitsign verify and gitsign verify-tag re-encode commit/tag objects through go-git's EncodeWithoutSignature before checking the signature, instead of verifying against the raw git object bytes. For malformed objects with duplicate tree headers, git-core and go-git parse different trees: git-core uses the first, go-git uses the second. A signature crafted over the go-git-normalized form (second tree) passes gitsign verify while git-core resolves the commit to a completely different tree. This breaks the invariant that a verified signature, the commit semantics git-core presents to users, and the object hash logged in Rekor all refer to the same content. Severity Medium (CVSS 3.1: 5.7) CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N - Attack Vector: Network — a malformed commit can be distributed via any accessible git remote - Attack Complexity: High — exploitation requires crafting malformed objects that also bypass git server fsck checks (not universally enabled) - Privileges…

Published by the source

8 May 2026, 22:38 UTC

Last modified by the source

15 May 2026, 23:49 UTC

Source last checked

26 Oct 2026, 15:22 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-7rmh-48mx-2vwc

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# Patch Next advisory brief: CVE-2026-44309

Advisory: gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits
IDs: CVE-2026-44309, GHSA-7rmh-48mx-2vwc
Record: https://patchnext.com/advisories/cve-2026-44309 (revision 1, source checked 26 Oct 2026, 15:22 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 5.3)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/sigstore/gitsign 0.16.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/sigstore/gitsign: affected < 0.16.0; fixed in 0.16.0

## Suggested inspection (read-only)
- Go github.com/sigstore/gitsign: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/sigstore/gitsign.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-7rmh-48mx-2vwc (GitHub-reviewed advisory GHSA-7rmh-48mx-2vwc lists affected ranges: Go github.com/sigstore/gitsign >=0 <0.16.0)

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