High severity · published Sep 28, 2026
CVE-2026-102273
PyJWT accepts public JWK containers as HMAC secrets
7.4
CVSS
0.2%
EPSS
No
On KEV
Description
PyJWT is a Python implementation of JSON Web Token standards. From 2.13.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because HMAC key guard only recognizes top-level public JWK forms and misses container representations. This occurs when an application allows HMAC and asymmetric algorithms and passes a public JWK container as the raw key. As a result, public asymmetric key material is accepted as the HMAC secret. Consequently, an attacker who knows the public key can forge a token with arbitrary authenticated claims. This issue is fixed in version 2.14.0.
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 7% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
PY
pyjwt · jpadilla
>= 2.13.0, < 2.14.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-102273
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-102273
x_refsource_CONFIRM
https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w2cx-738m-mc7w
x_refsource_MISC
https://github.com/jpadilla/pyjwt/commit/801cd128528c62d9b23fcd161d1a2e1c17982f95
x_refsource_MISC
https://github.com/jpadilla/pyjwt/releases/tag/2.14.0
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