Improper Handling of Highly Compressed Data (Data Amplification) Affecting org.http4k:http4k-core package, versions [,6.49.0.0)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-JAVA-ORGHTTP4K-18905378
- published18 Aug 2026
- disclosed17 Aug 2026
- creditUnknown
Introduced: 17 Aug 2026
CVE-2026-53659 (opens in a new tab)How to fix?
Upgrade org.http4k:http4k-core to version 6.49.0.0 or higher.
Overview
Affected versions of this package are vulnerable to Improper Handling of Highly Compressed Data (Data Amplification) through the Body.gunzipped() and Body.gunzippedStream() paths in core/core/src/main/kotlin/org/http4k/filter/Gzip.kt and the RequestFilters.GunZip request filter in core/core/src/main/kotlin/org/http4k/filter/RequestFilters.kt. An attacker can exhaust JVM heap and deny service to other clients by sending a small gzip-encoded request body that expands to an arbitrarily large payload.
Notes
- Additional fixes have been released for 4.x and 5.x streams under LTS for Enterprise, (contact enterprise@http4k.org)
Workarounds
- Replace the
GZip/GunZipfilters with custom versions that wrap the decompressedInputStreamin a size-limited reader, to stop gzip bombs from expanding into enough data to exhaust JVM heap. - Strip gzip-encoded request support at the edge, such as at a CDN, reverse proxy, or load balancer, to prevent unauthenticated clients from delivering the compressed request bodies that trigger the decompression DoS.