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01 Record

CVE-2025-59420

Authlib: JWS/JWT accepts unknown crit headers (RFC violation → possible authz bypass)

HighPUBLISHEDCNA: GitHub_M
CNA base score7.5 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

02 Description

Authlib: JWS/JWT accepts unknown crit headers (RFC violation → possible authz bypass)

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.26% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 17.8% of scored records. A rank, not a probability.
NVD base score
7.5 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD analysis status
Modified. NVD last modified this record on 2026-10-19.
Red Hat severity
Important. Red Hat's rating for its own products, not a CVSS rating.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2025-09-22 17:28Z1 YR AGO
Last updated
2025-11-03 17:45Z12 MO AGO
Reserved
2025-09-15
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
High (CVSS 7.5)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Weaknesses
  • CWE-345Insufficient Verification of Data AuthenticityClass
  • CWE-863Incorrect AuthorizationClass
  • CWE-440Expected Behavior ViolationBase
Data version
5.2
Document digest
df91538096662c7c03b453ae2b318ae2da2af0cc24dff552158c30fb6e7562c4

05 Affected products

VendorProductVersionsPlatforms
authlibauthlib< 1.6.4—

06 References

07 Fixed in

Debian 12

  • python-authlib
    Fixed in 1.2.0-1+deb12u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 13

  • python-authlib
    Fixed in 1.6.0-1+deb13u1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Debian 14

  • python-authlib
    Fixed in 1.6.4-1

Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 25.10

  • python-authlib
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu 26.10

  • python-authlib
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 22.04 LTS

  • python-authlib
    Fixed in 0.15.5-1ubuntu0.1~esm1
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 24.04 LTS

  • python-authlib
    Fixed in 1.3.0-1ubuntu0.1~esm1
    Available with Ubuntu Pro: https://ubuntu.com/pro

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

Ubuntu Pro 26.04 LTS

  • python-authlib
    No fix yet

Source: Ubuntu, Canonical Ltd. Licensed under CC BY-SA 4.0. Received through OSV.dev. Reformatted by exploit.cc.

A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.