CVE-2026-39373

Public on 2026-04-07
Modified on 2026-04-09
Description
JWCrypto implements JWK, JWS, and JWE specifications using python-cryptography. Prior to 1.5.7, an unauthenticated attacker can exhaust server memory by sending crafted JWE tokens with ZIP compression. The existing patch for CVE-2024-28102 limits input token size to 250KB but does not validate the decompressed output size. An unauthenticated attacker can cause memory exhaustion on memory-constrained systems. A token under the 250KB input limit can decompress to approximately 100MB. This vulnerability is fixed in 1.5.7.
Severity
Important severity
Important
See what this means
CVSS v3 Base Score
7.5
See breakdown

Affected Packages

Platform Package Release Date Advisory Status
Amazon Linux 2 - Core python-jwcrypto Pending Fix
Amazon Linux 2023 python-jwcrypto Pending Fix

CVSS Scores

Score Type Score Vector
Amazon Linux CVSSv3 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H