CVE-2026-101918PyJWT: Unauthenticated RecursionError DoS in pre-verification payload parse (PyJWKClient.get_signing_key_from_jwt / verify_signature=False)
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It affects jpadilla pyjwt and 1 other product. Add what you run to find out whether that includes you.
EPSS puts the chance of exploitation in the next 30 days at 0.36%, higher than 28% of scored CVEs.
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PyJWT is a Python implementation of JSON Web Token standards. From 2.0.0a1 until 2.15.0, PyJWT PyJWKClient.get_signing_key_from_jwt is affected because payload parser catches ValueError but not RecursionError. This occurs when an attacker-controlled recursively nested payload reaches json.loads. As a result, documented PyJWT exception handling does not contain the failure. Consequently, an unauthenticated request can raise an exception that may produce an HTTP 500 response. The advisory-defined affected implementation also includes jwt/api_jwt.py, verify_signature=False. This issue is fixed in version 2.15.0.
- CVSS
- 5.3 MEDIUM (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
- Weakness (CWE)
- CWE-248
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- 0.36% (percentile 28)
- Assigned by
- GitHub_M
- NVD analysis
- Analyzed
- Record last updated
- Sep 29, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
jpadilla pyjwt jpadilla:pyjwt (from the name) | from 2.0.0a1, < 2.15.0 | CNA record |
pyjwt_project pyjwt pyjwt_project:pyjwt | from 2.0.0 before 2.15.0 | NVD |
References
- https://github.com/jpadilla/pyjwt/security/advisories/GHSA-42vr-xj54-vc7vx-refsource-confirm, exploit, mitigation, vendor-advisory
- https://github.com/jpadilla/pyjwt/commit/5fde08a6cf906aa7698de2d6391d88b73006b17bx-refsource-misc, patch
- https://github.com/jpadilla/pyjwt/releases/tag/2.15.0x-refsource-misc, product, release-notes
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.