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VulnerabilityPublished

CVE-2026-102266: jpadilla pyjwt · Improper Verification of Cryptographic Signature

Affects jpadilla pyjwtSource CVE Database V5

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Not known to be exploited · CVSS 7.4 High : upgrade to 2.14.0 soon.

Data as of 12 Nov 2026, 23:24 UTC

CVSS 3.1 base score
7.4High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 13% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.14.0
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. Weaponized: 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 13 Nov 2026.

What to do

Upgrade jpadilla pyjwt to 2.14.0.

Affected software

ProductAffectedFixed in
jpadillapyjwtAffected
  • >=2.13.0 <2.14.0
Fixed in
  • 2.14.0
PyPIpyjwtpkg:pypi/pyjwtOther threatsAffected
  • >=2.13.0 <2.14.0
Fixed in
  • 2.14.0

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

AI-suggested

As a mitigation, ensure that no empty or zero-length symmetric keys are present in JWK or JWKS configurations. Validate and sanitize all keys before use, and avoid using empty Base64URL keys. Consider upgrading to a fixed version once available or apply custom validation to reject empty keys in the PyJWK path.

Description

CVE-2026-102266 is a vulnerability in PyJWT 2.13.0 where verification of HS256 tokens using an empty symmetric octet JWK key bypasses the intended empty key rejection. While raw empty HMAC keys are rejected, empty keys supplied via PyJWK objects are accepted, allowing attackers to forge valid HS256 JWTs if the application uses an empty key in its JWK set. This occurs because the PyJWK verification path does not invoke the empty key validation, enabling signature verification with a zero-length key.

References

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