CVE-2026-53659: high-severity vulnerability in http4k
http4k: Unbounded gzip decompression in `ServerFilters.GZip` / `RequestFilters.GunZip` allowed memory-exhaustion DoS
Published
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.6%
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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
http4k · http4kRelated CVEs — http4k
In the same product, most dangerous first.
CVE-2024-55875CRITICALhttp4k has a potential XXE (XML External Entity Injection) vulnerabilityEPSS 1.9%CVE-2026-54148HIGHhttp4k: `DigestAuthProvider.verify` did not bind to request URIEPSS 0.6%CVE-2026-100724MEDIUMhttp4k before 6.49.0.0 Host Header Routing Bypass via reverseProxyEPSS 0.3%CVE-2026-100834HIGHhttp4k before 6.48.0.0 Digest Authentication Replay Protection BypassEPSS 0.3%CVE-2026-120316HIGHhttp4k before 6.62.0.0-ee Path Traversal via ThymeleafTemplates Template ResolutionEPSS 0.3%CVE-2026-54147MEDIUMhttp4k: `DigestAuthProvider.verify` ignored configured algorithm and did not bind to request URIEPSS 0.3%