Skip to main content
CVE-2026-102271VulnerabilityPublished Updated

From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual

Affects pyjwtSource GCVE Database

0
Authoritative record:CVE-2026-102271· High 7.4

Not known to be exploited · CVSS 7.4 High · fixed in 1.3.0-1ubuntu0.1+esm3 : 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 1.3.0-1ubuntu0.1+esm3, 1.5.3+ds1-1ubuntu0.1+esm3, 1.7.1-2ubuntu2.1+esm3 +4
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 to a fixed release listed under Affected software.

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
Ubuntu 24.04 LTSpyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=nobleOther threatsAffected
  • <2.7.0-1ubuntu0.3
Fixed in
  • 2.7.0-1ubuntu0.3
Ubuntu 22.04 LTSpyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=jammyOther threatsAffected
  • <2.3.0-1ubuntu0.5
Fixed in
  • 2.3.0-1ubuntu0.5
Ubuntu Pro 20.04 LTSpyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=esm-infra/focalOther threatsAffected
  • <1.7.1-2ubuntu2.1+esm3
Fixed in
  • 1.7.1-2ubuntu2.1+esm3
Ubuntu Pro 18.04 LTSpyjwtpkg:deb/ubuntu/pyjwt?arch=source&distro=esm-infra/bionicOther threatsAffected
  • <1.5.3+ds1-1ubuntu0.1+esm3
Fixed in
  • 1.5.3+ds1-1ubuntu0.1+esm3

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 users should update PyJWT to version 2.14.0 or later. Ubuntu users should apply the security updates provided in the following package versions: 1.3.0-1ubuntu0.1+esm3, 1.5.3+ds1-1ubuntu0.1+esm3, 1.7.1-2ubuntu2.1+esm3, 2.3.0-1ubuntu0.5, 2.7.0-1ubuntu0.3, 2.10.1-4ubuntu1.2, or 2.13.0-1ubuntu1. Standard system updates will apply these fixes. No additional mitigation is required beyond applying these patches.

Description

PyJWT versions from 2.4.0 up to 2.14.0 contain a vulnerability in the HMACAlgorithm.prepare_key function. The issue arises because the asymmetric-key guard relies on textual markers that are missing from DER-encoded public keys. When an application mixes HMAC and asymmetric algorithms and uses a DER public key as the shared verification key, PyJWT mistakenly uses the public DER bytes as an HMAC secret. This flaw allows an attacker who knows the public key to forge authenticated HMAC tokens. The vulnerability is fixed in version 2.14.0.

References

Community reviews

Loading reviews…