CVE-2026-44309

Name	CVE-2026-44309
Description	Gitsign is a keyless Sigstore to signing tool for Git commits with your a GitHub / OIDC identity. Prior to 0.16.0, 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. This vulnerability is fixed in 0.16.0.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1136789

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
gitsign (PTS)	trixie	0.13.0-2	vulnerable
	forky, sid	0.16.0-1	fixed

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
gitsign	source	(unstable)	0.16.0-1			1136789

Notes

[trixie] - gitsign <no-dsa> (Minor issue)
https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc
Fixed by: https://github.com/sigstore/gitsign/commit/3c84d87240644b5c62b3b3d79177ae64448591c8 (v0.16.0)