Vulnerability Description
http4k is a functional toolkit for Kotlin HTTP applications. Prior to 4.51.0.0, 5.42.0.0, and 6.49.0.0, ServerFilters.GZip, RequestFilters.GunZip, and the underlying Gzip request-body decompression functions impose no limit on decompressed size. An unauthenticated client can send a small gzip-encoded request body that expands to gigabytes, exhausting the JVM heap and denying service to other clients. The fix uses SizeLimitedInputStream to enforce a default 10 MiB limit, causes ServerFilters.GZip and RequestFilters.GunZip to return 413 Request Entity Too Large, and causes other decompression paths to throw SizeLimitExceededException. This issue is fixed in versions 4.51.0.0, 5.42.0.0, and 6.49.0.0.
CVSS Score
HIGH
Related Weaknesses (CWE)
References
- https://github.com/http4k/http4k/commit/2618fe08f9801353012561ae1f1382fa2d37bac9
- https://github.com/http4k/http4k/commit/9f9e02f8efbbe04e0c70f1c46eef5d9d9067ea5b
- https://github.com/http4k/http4k/releases/tag/6.49.0.0
- https://github.com/http4k/http4k/security/advisories/GHSA-g4w2-6h2r-3m3w
FAQ
What is CVE-2026-53659?
CVE-2026-53659 is a vulnerability with a CVSS score of 7.5 (HIGH). http4k is a functional toolkit for Kotlin HTTP applications. Prior to 4.51.0.0, 5.42.0.0, and 6.49.0.0, ServerFilters.GZip, RequestFilters.GunZip, and the underlying Gzip request-body decompression fu...
How severe is CVE-2026-53659?
CVE-2026-53659 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-53659?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.