{"cve":"CVE-2026-48525","nvd":{"published":"2026-05-28T16:16:29.533","modified":"2026-10-25T23:10:00.167","status":"Analyzed","description":"PyJWT is a JSON Web Token implementation in Python. From 2.8.0 to 2.12.1, when verifying detached JWS tokens using the unencoded-payload option (\"b64\": false, RFC 7797), PyJWT performs Base64URL decoding of the compact-serialization payload segment before enforcing the detached-payload rules. For b64=false, PyJWT later discards that decoded payload and replaces it with the caller-provided detached_payload. In practice, this turns the middle segment into an attacker-controlled “work amplifier”: a remote client can supply an arbitrarily large Base64URL payload segment that forces CPU work + memory allocations even if the signature is invalid. This creates an unauthenticated DoS vector against any endpoint that verifies detached JWS using PyJWT. This vulnerability is fixed in 2.13.0.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","score":5.3},"cwes":["CWE-400"],"references":["https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w7vc-732c-9m39","https://github.com/jpadilla/pyjwt/security/advisories/GHSA-w7vc-732c-9m39"],"products":["pyjwt_project:pyjwt"],"source":"nvd","synced_at":"2026-10-25T23:44:33.281319194+00:00"},"epss":{"cve":"CVE-2026-48525","score":0.0037,"percentile":0.30677,"date":"2026-10-25"},"kev":null,"osv":[{"id":"GHSA-w7vc-732c-9m39","url":"https://osv.dev/vulnerability/GHSA-w7vc-732c-9m39","summary":"PyJWT: Unauthenticated DoS via unbounded Base64URL decoding of unused payload segment in b64=false detached JWS","modified":"2026-09-10T03:50:50.801195449Z","packages":[{"ecosystem":"PyPI","name":"pyjwt","purl":"pkg:pypi/pyjwt","ranges":[">=2.8.0 <2.13.0"],"fixed":["2.13.0"]}]},{"id":"PYSEC-2026-178","url":"https://osv.dev/vulnerability/PYSEC-2026-178","summary":"","modified":"2026-06-02T12:15:10.739334903Z","packages":[{"ecosystem":"PyPI","name":"pyjwt","purl":"pkg:pypi/pyjwt","ranges":[">=2.8.0 <2.13.0"],"fixed":["2.13.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}