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{"bugzilla": {"description": "org.http4k/http4k-core: http4k: Denial of Service via unbounded gzip decompression", "id": "2533236", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2533236"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.5", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-409", "details": ["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.", "A flaw was found in http4k, a functional toolkit for Kotlin HTTP applications. The `ServerFilters.GZip` and `RequestFilters.GunZip` functions, along with underlying Gzip request-body decompression, do not limit the decompressed size of incoming data. An unauthenticated client can exploit this by sending a small, specially crafted gzip-encoded request body that expands to a very large size, consuming excessive Java Virtual Machine (JVM) memory. This can lead to a Denial of Service (DoS) condition, making the application unavailable to other legitimate clients."], "name": "CVE-2026-53659", "package_state": [{"cpe": "cpe:/a:redhat:jboss_fuse:7", "fix_state": "Affected", "package_name": "http4k-core", "product_name": "Red Hat Fuse 7"}], "public_date": "2026-09-14T17:29:57Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-53659\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-53659\nhttps://github.com/http4k/http4k/commit/2618fe08f9801353012561ae1f1382fa2d37bac9\nhttps://github.com/http4k/http4k/commit/9f9e02f8efbbe04e0c70f1c46eef5d9d9067ea5b\nhttps://github.com/http4k/http4k/releases/tag/6.49.0.0\nhttps://github.com/http4k/http4k/security/advisories/GHSA-g4w2-6h2r-3m3w"], "statement": "This vulnerability is rated as Important as it allows an unauthenticated remote attacker to cause a denial of service in applications utilizing the http4k library for HTTP request processing. By sending a specially crafted, compressed request body, an attacker can trigger unbounded decompression, leading to excessive memory consumption and application unavailability.", "threat_severity": "Important"}