CVE-2026-48525

MEDIUM
MEDIUM Priority: 0.02 BB Relevance: 71/100
Published: 2026-05-28 Modified: 2026-10-25 First seen: 2026-10-29 Status: active

Attack Surface

Network Low Complexity No Auth No Interaction

CVSS Vector Breakdown

AV: Network
AC: Low
PR: None
UI: None
S: Unchanged
C: None
I: None
A: Low

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.

Weakness Classification (1)

Affected Software (1)

VendorProductVersion
pyjwt_project pyjwt 2.8.0 – 2.12.1

References & Advisories (1)

Bug Bounty Relevance

71 / 100
✓ Network accessible
✓ No authentication
✓ Low complexity
✓ No user interaction

CVSS Score

5.3 / 10.0 v3.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS — Exploitation Probability

0.37%
Raw Score 0.003700
Percentile 30.9%
Date 2026-10-29

EPSS Trend

2026-10-29
0.00370
2026-10-28
0.00370

Intelligence Sources

nvd ref →