PT-2026-53594 · Pypi · Rfc3161-Client

Published 2026-06-29 · Updated 2026-06-29

OSV

CVSS v4.0

9.3

Critical

Base vector

AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N

Impact

rfc3161-client 1.0.2 and earlier contain a flaw in their timestamp response signature verification logic. In particular, it performs chain verification against the TSR's embedded certificates up to the trusted root(s), but fails to verify the TSR's own signature against the timestamping leaf certificates. Consequently, vulnerable versions perform insufficient signature validation to properly consider a TSR verified, as the attacker can introduce any TSR signature so long as the embedded leaf chains up to some root TSA.

Patches

Users should immediately upgrade to rfc3161-client 1.0.3 or later.

Workarounds

There is no workaround possible. Users should immediately upgrade to a fixed version.

Fix

Related Identifiers

PYSEC-2026-525

Affected Products

Rfc3161-Client

References · 7

• https://nvd.nist.gov/vuln/detail/CVE-2025-52556 · Security Note
• https://osv.dev/vulnerability/PYSEC-2026-525 · Vendor Advisory
• https://github.com/trailofbits/rfc3161-client/commit/724a184f953e3f171f85cb223871172b41b0d0dc · Note
• https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-6qhv-4h7r-2g9m · Note
• https://github.com/trailofbits/rfc3161-client · Note
• https://pypi.org/project/rfc3161-client · Note
• https://github.com/advisories/GHSA-6qhv-4h7r-2g9m · Note