Improper handling of highly compressed data in jwcrypto - CVE-2026-39373

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Main Vulnerability Database Vulnerabilities #VU125313

Improper handling of highly compressed data in jwcrypto - CVE-2026-39373

Published: April 8, 2026


Vulnerability identifier: #VU125313
CSH Severity: Medium
CVSS v4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-39373
CWE-ID: CWE-409
Exploitation vector: Remote access
Exploit availability: No public exploit available

Vulnerability details

The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper handling of highly compressed data in the deserialize function when processing crafted JWE tokens with ZIP compression. A remote attacker can send a specially crafted JWE token to cause a denial of service.

Memory-constrained systems are more likely to be affected.


Affected software

jwcrypto
openEuler
Anolis OS
python-jwcrypto
python3-jwcrypto
python-jwcrypto-help
python3-jwcrypto-doc

How to mitigate CVE-2026-39373

Install security update from vendor's website.

jwcrypto - update to 1.5.7
python-jwcrypto - addressed in versions 1.4.2-4, 1.5.0-4
python3-jwcrypto - addressed in versions 1.4.2-4, 1.5.0-4
python-jwcrypto-help - update to 1.5.0-4
python3-jwcrypto - update to 1.5.7-1
python3-jwcrypto-doc - update to 1.5.7-1

External References

Related Security Bulletins