CVE-2026-39373
low-risk
Published 2026-04-07
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.
Do I need to act?
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0.07% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10
Medium
NETWORK
/ LOW complexity
Affected Products (1)
Jwcrypto
Affected Vendors
References (1)
26
/ 100
low-risk
Severity
21/34 · High
Exploitability
0/34 · Minimal
Exposure
5/34 · Minimal