gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits_CVE-2026-44309

{
    "lastseen": "",
    "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.",
    "published": "2026-05-15T16:22:51.260Z",
    "modified": "2026-05-15T16:22:51.260Z",
    "type": "cve",
    "title": "gitsign verify accepts signatures over go-git-normalized bytes, enabling trust confusion on malformed commits",
    "source": "GitHub_M",
    "references": "https://github.com/sigstore/gitsign/security/advisories/GHSA-7rmh-48mx-2vwc",
    "id": "CVE-2026-44309",
    "bulletinFamily": "",
    "cwe": [
        "CWE-347",
        "CWE-295"
    ],
    "cvelist": null,
    "sourceData": "sigstore gitsign < 0.16.0",
    "sourceHref": "",
    "cvss": {
        "score": 5.3,
        "severity": "MEDIUM",
        "vector": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
        "version": "3.1"
    },
    "cvss2": [],
    "cvss3": {
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        "baseScore": 0,
        "baseSeverity": "",
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        "attackComplexity": "",
        "privilegesRequired": "",
        "userInteraction": "",
        "scope": "",
        "confidentialityImpact": "",
        "integrityImpact": "",
        "availabilityImpact": "",
        "cvssV3": {
            "version": "",
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        }
    },
    "href": "",
    "category_name": "CVE",
    "post_link": "",
    "product": "gitsign",
    "version": "< 0.16.0",
    "vendor": "sigstore",
    "ai_description": "",
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    "ai_score": 0
}