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CVE-2026-102266VulnerabilityPublished Updated

Pyjwt: From 2.13.0 until 2.14.0, HMACAlgorithm.from_jwk is affected because PyJWK verification path used the decoded

Affects pyjwtSource GCVE Database

0
Authoritative record:CVE-2026-102266· High 7.4

Not known to be exploited · CVSS 7.4 High · fixed in 2.13.0-1ubuntu1 : patch pyjwt soon.

Data as of 27 Oct 2026, 14:30 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 2.13.0-1ubuntu1, 2.10.1-4ubuntu1.2
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 28 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade the Ubuntu pyjwt to 2.13.0-1ubuntu1 (package) or 2.10.1-4ubuntu1.2 (package).

Affected software

ProductAffectedFixed in
Ubuntu 26.10pyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=stonkingOther threatsAffected
  • <2.13.0-1ubuntu1
Fixed in
  • 2.13.0-1ubuntu1
Ubuntu 26.04 LTSpyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=resoluteOther threatsAffected
  • <2.10.1-4ubuntu1.2
Fixed in
  • 2.10.1-4ubuntu1.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available and has been released in PyJWT version 2.14.0. Users should update to this version or later. Ubuntu users should apply the security updates provided in packages python3-jwt 2.13.0-1ubuntu1 or python3-jwt 2.10.1-4ubuntu1.2 as appropriate. Standard system updates will apply these fixes. No additional mitigation actions are required beyond applying these updates.

Description

PyJWT versions from 2.13.0 until 2.14.0 contain a vulnerability in the HMACAlgorithm.from_jwk function where the verification path uses a decoded key without proper prepare_key validation. This flaw allows an attacker to exploit a trusted JWK Set containing an oct entry with an empty key value, enabling the signing of HMAC tokens with a zero-length key that PyJWT accepts. As a result, attackers can forge tokens with arbitrary authenticated claims. The issue is fixed in PyJWT version 2.14.0.

References

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