PYSEC-2026-525

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Import Source
https://github.com/pypa/advisory-database/blob/main/vulns/rfc3161-client/PYSEC-2026-525.yaml
JSON Data
https://api.osv.dev/v1/vulns/PYSEC-2026-525
Aliases
Published
2026-06-29T11:50:38.536479Z
Modified
2026-06-29T12:15:43.924593912Z
Severity
  • 9.3 (Critical) CVSS_V4 - CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N CVSS Calculator
Summary
rfc3161-client has insufficient verification for timestamp response signatures
Details

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.

References

Affected packages

PyPI / rfc3161-client

Package

Affected ranges

Type
ECOSYSTEM
Events
Introduced
0Unknown introduced version / All previous versions are affected
Fixed
1.0.3

Affected versions

0.*
0.0.2
0.0.3
0.0.4
0.1.0
0.1.1
0.1.2
1.*
1.0.0
1.0.1
1.0.2

Database specific

last_known_affected_version_range
"<= 1.0.2"
source
"https://github.com/pypa/advisory-database/blob/main/vulns/rfc3161-client/PYSEC-2026-525.yaml"