EUVD-2026-32919CVSS VectorNVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Lifecycle Timeline
2DescriptionNVD
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.
AnalysisAI
Uncontrolled resource consumption in PyJWT 2.8.0-2.12.1 exposes any service that verifies detached JWS tokens to unauthenticated denial-of-service. When the unencoded-payload extension (b64=false, RFC 7797) is in use, PyJWT unnecessarily Base64URL-decodes the compact-serialization payload segment before discarding it in favor of the caller-supplied detached payload - turning that segment into an attacker-controlled amplifier for CPU and memory exhaustion regardless of signature validity. …
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