PyJWT is a Python implementation of JSON Web Token standards. From 2.4.0 until 2.14.0, PyJWT HMACAlgorithm.prepare_key is affected because asymmetric-key guard relies on textual markers that are absent from DER encoding. This occurs when an application mixes HMAC and asymmetric algorithms and supplies a DER public key as the shared verification key. As a result, PyJWT uses public DER bytes as an HMAC secret. Consequently, an attacker who knows the public key can forge authenticated HMAC tokens. This issue is fixed in version 2.14.0.
{
"cna_assigner": "GitHub_M",
"cwe_ids": [
"CWE-347"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/102xxx/CVE-2026-102271.json"
}{
"extracted_events": [
{
"cpe": "cpe:2.3:a:pyjwt_project:pyjwt:*:*:*:*:*:*:*:*",
"range": [
{
"introduced": "2.4.0"
},
{
"fixed": "2.14.0"
}
],
"source": "CPE_RANGE"
},
{
"range": [
{
"fixed": "2798504fa2663364573cf2d1043d8d7fef389499"
}
],
"source": "REFERENCES_COMMIT"
},
{
"original_tag": "2.14.0",
"range": [
{
"fixed": "c6fe464b356ff4b1ebc9ba62172d331a40aa27df"
}
],
"source": "REFERENCES_TAG"
}
]
}