CVE-2026-53659 http4k - Denial of Service

http4k < 4.51.0.0, 5.42.0.0, and 6.49.0.0 contain a denial of service caused by unlimited gzip decompression size in ServerFilters.GZip and RequestFilters.GunZip, letting unauthenticated clients exhaust JVM heap, exploit requires sending crafted gzip request.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.63% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
14 September 2026
Updated
15 October 2026
Weakness
CWE-409

Vendor fix

Update to versions 4.51.0.0, 5.42.0.0, or 6.49.0.0 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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