CVE-2026-39373

Name	CVE-2026-39373
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)
Debian Bugs	1133006

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
python-jwcrypto (PTS)	bullseye	0.8.0-1	vulnerable
	bullseye (security)	0.8.0-1+deb11u1	vulnerable
	bookworm	1.1.0-1+deb12u1	vulnerable
	forky, sid, trixie	1.5.6-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
python-jwcrypto	source	(unstable)	(unfixed)			1133006

Notes

https://github.com/latchset/jwcrypto/security/advisories/GHSA-fjrm-76x2-c4q4
Fixed by: https://github.com/latchset/jwcrypto/commit/25db861d8b29434838669a94a843af03d29ea6ed (v1.5.7)