sigstore-js: Insufficient Verification of Data Authenticity

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

sigstore-js provides JavaScript libraries for interacting with Sigstore services. Prior to 3.1.1, @sigstore/verify derives a transparency-log timestamp from tlogEntries[].integratedTime for bundle v0.2 inclusionProof-only entries even though the inclusion proof path does not cryptographically bind integratedTime, allowing an attacker who can supply an untrusted bundle to influence certificate validity and timestampThreshold verification decisions. This issue is fixed in version 3.1.1.

Source published

14 Jul 2026 20:39:05 UTC

Source modified

15 Jul 2026 14:26:01 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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CVSS 3.1 · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

sigstore-js provides JavaScript libraries for interacting with Sigstore services. Prior to 3.1.1, @sigstore/verify derives a transparency-log timestamp from tlogEntries[].integratedTime for bundle v0.2 inclusionProof-only entries even though the inclusion proof path does not cryptographically bind integratedTime, allowing an attacker who can supply an untrusted bundle to influence certificate validity and timestampThreshold verification decisions. This issue is fixed in version 3.1.1.

Source published

14 Jul 2026 21:17:01 UTC

Source modified

24 Oct 2026 21:10:00 UTC

Observed here

25 Oct 2026 12:17:32 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 6.5 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

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`. ## impact If 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. ## affected code - `packages/verify/src/bundle/index.ts` (adds a transparency-log timestamp whenever `integratedTime != 0`) - `packages/verify/src/timestamp/index.ts` (converts `integratedTime` to a `Date`) - `packages/verify/src/verifier.ts` (verifies timestamps before verifying tlog inclusion) - `packages/verify/src/tlog/index.ts` + `packages/verify/src/tlog/set.ts` (only the inclusionPromise/set path binds `integratedTime`) ## proof of concept The 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. repro: 1) extract `poc.zip` into a fresh directory and run the make targets: ```bash unzip poc.zip -d poc cd poc/poc-F-SIG-JS-TLOGTIME-001 make canonical make control ``` 2) confirm `canonical.log` includes: ``` [CALLSITE_HIT]: [PROOF_MARKER]: ``` 3) confirm `control.log` includes: ``` [NC_MARKER]: ``` ## suggested fix Only 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). [poc.zip](https://github.com/user-attachments/files/25643656/poc.zip) [PR_DESCRIPTION.md](https://github.com/user-attachments/files/25643660/PR_DESCRIPTION.md) [SUBMISSION.md](https://github.com/user-attachments/files/25643662/SUBMISSION.md)

Source published

1 Jul 2026 19:57:45 UTC

Source modified

10 Sep 2026 03:51:12 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N

Publisher rating · MODERATE