{"id":"CVE-2026-49834","aliases":["GHSA-9vcr-p3rj-q5q6"],"title":"sigstore-go has a multi-log threshold bypass via single compromised log","summary":"sigstore-go has a multi-log threshold bypass via single compromised log","severity":"medium","cvss":5.9,"cwe":["CWE-345"],"vendor":"sigstore","product":"github.com/sigstore/sigstore-go","ecosystem":"go","affected":["github.com/sigstore/sigstore-go <= 1.1.4"],"patched":["github.com/sigstore/sigstore-go 1.2.0"],"published":"2026-07-09","updated":"2026-07-09","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-9vcr-p3rj-q5q6","references":[{"url":"https://github.com/sigstore/sigstore-go/security/advisories/GHSA-9vcr-p3rj-q5q6"},{"url":"https://github.com/advisories/GHSA-9vcr-p3rj-q5q6"}],"tags":["ghsa","go"],"ingestedAt":"2026-07-09T23:53:27.219Z","slug":"CVE-2026-49834","body":"## Overview\n\n### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nA verifier configured with WithTransparencyLog(N>1) or WithSignedCertificateTimestamps(N>1) expected defense-in-depth against the compromise of a single log instance. However, threshold counting counted verified witnesses per-entry or per-validation-path rather than per-log-authority.\n\nAs a result, a single compromised transparency log could forge multiple entries with different indices, and a single compromised CT log could verify multiple times (either across multiple certificate chains or via multiple embedded SCTs), fully satisfying the multi-log threshold requirements and defeating the multi-log policy.\n\nNote that this does not affect Cosign, as Cosign sets a threshold of 1.\n\n### Patches\n_Has the problem been patched? What versions should users upgrade to?_\n\nUpgrade to v1.1.5.\n\n### Workarounds\n_Is there a way for users to fix or remediate the vulnerability without upgrading?_\n\nThere is no workaround, beyond relying on trusted logs.\n\n## Affected packages\n\n- `github.com/sigstore/sigstore-go <= 1.1.4`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `github.com/sigstore/sigstore-go 1.2.0`","depth":"sunlit","depthScore":32,"depthScoreParts":{"impact":32.5,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}