🛡️ CVE-2026-48816 — verify

🟡 CVSS 6.5 — Medium ✅ No Known Exploit CWE-345 NVD
6.5
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

sigstore-js has Insufficient Verification of Data Authenticity

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)

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is low, an attacker needs low-level privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality none, integrity high, availability none.

Weakness class

CVE-2026-48816 is classified as CWE-345: Insufficient Verification of Data Authenticity. Data is trusted without confirming it really came from the claimed source and was not altered.

Affected software

CVE-2026-48816 is recorded against 2 packages.

  • @sigstore/verify
  • unknown

Timeline and source

Published on 1 July 2026 and last revised on 3 July 2026. No public exploit is currently recorded for this entry. Record sourced from NVD.

References

github.com (Web)
github.com (Package)

Details

Severity Medium
CVSS Score 6.5
CVSS Vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
CWE CWE-345
Public Exploit ✅ No
Source NVD
Published 2026-07-01
Updated 2026-08-12
Modified 2026-07-03
Fix URL N/A

Affected Packages

Software From version Fixed in
@sigstore/verify — —
unknown — —

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