{"id":"GHSA-xgjw-pm74-86q4","summary":"sigstore-js has Insufficient Verification of Data Authenticity","details":"sigstore-js derives a transparency-log timestamp from `tlogEntries[].integratedTime` and uses it to validate certificate validity windows and satisfy `timestampThreshold`. For bundle v0.2, a tlog entry can be inclusionProof-only (no signed inclusionPromise/set), and the inclusion proof path does not cryptographically bind `integratedTime`. As a result, an attacker who can supply an untrusted bundle can influence time-based verification decisions by choosing `integratedTime`.\n\n## impact\nIf a consumer accepts attacker-provided bundle v0.2 inputs and relies on tlog-derived timestamps for certificate validity checks, verification can be influenced by an unauthenticated timestamp value. This is a trust gap: `integratedTime` is treated as a trusted observer timestamp under inclusionProof-only mode even though only the signed inclusionPromise/set path binds it.\n\n## affected code\n- `packages/verify/src/bundle/index.ts` (adds a transparency-log timestamp whenever `integratedTime != 0`)\n- `packages/verify/src/timestamp/index.ts` (converts `integratedTime` to a `Date`)\n- `packages/verify/src/verifier.ts` (verifies timestamps before verifying tlog inclusion)\n- `packages/verify/src/tlog/index.ts` + `packages/verify/src/tlog/set.ts` (only the inclusionPromise/set path binds `integratedTime`)\n\n## proof of concept\nThe attached `poc.zip` contains a self-contained harness that reproduces the behavior on the pinned commit and includes both a canonical test and a negative control.\n\nrepro:\n1) extract `poc.zip` into a fresh directory and run the make targets:\n\n```bash\nunzip poc.zip -d poc\ncd poc/poc-F-SIG-JS-TLOGTIME-001\nmake canonical\nmake control\n```\n\n2) confirm `canonical.log` includes:\n\n```\n[CALLSITE_HIT]:\n[PROOF_MARKER]:\n```\n\n3) confirm `control.log` includes:\n\n```\n[NC_MARKER]:\n```\n\n## suggested fix\nOnly treat `integratedTime` as a trusted timestamp when it is cryptographically bound (for example, via a verified signed inclusionPromise/set). For inclusionProof-only entries, do not count `integratedTime` toward `timestampThreshold`, and do not use it for certificate validity decisions unless there is another signed time source (for example, an rfc3161 timestamp).\n\n[poc.zip](https://github.com/user-attachments/files/25643656/poc.zip)\n[PR_DESCRIPTION.md](https://github.com/user-attachments/files/25643660/PR_DESCRIPTION.md)\n[SUBMISSION.md](https://github.com/user-attachments/files/25643662/SUBMISSION.md)","aliases":["CVE-2026-48816"],"modified":"2026-08-24T00:35:11.546138443Z","published":"2026-07-01T19:57:45Z","database_specific":{"severity":"MODERATE","github_reviewed":true,"github_reviewed_at":"2026-07-01T19:57:45Z","nvd_published_at":null,"cwe_ids":["CWE-345"]},"references":[{"type":"WEB","url":"https://github.com/sigstore/sigstore-js/security/advisories/GHSA-xgjw-pm74-86q4"},{"type":"PACKAGE","url":"https://github.com/sigstore/sigstore-js"}],"affected":[{"package":{"name":"@sigstore/verify","ecosystem":"npm","purl":"pkg:npm/%40sigstore/verify"},"ranges":[{"type":"SEMVER","events":[{"introduced":"3.1.0"},{"fixed":"3.1.1"}]}],"versions":["3.1.0"],"database_specific":{"source":"https://github.com/github/advisory-database/blob/main/advisories/github-reviewed/2026/07/GHSA-xgjw-pm74-86q4/GHSA-xgjw-pm74-86q4.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N"}]}