http4k: Unbounded gzip decompression in `ServerFilters.GZip` / `RequestFilters.GunZip` allowed memory-exhaustion DoS
Impact
ServerFilters.GZip and RequestFilters.GunZip (and the underlying Gzip functions used to decompress request bodies) did not impose any cap on the decompressed size. A small malicious gzip-encoded request body (on the order of kilobytes) could decompress to gigabytes, exhausting the JVM heap and denying service to other clients.
Who is affected: any http4k server that accepts gzip-encoded requests via ServerFilters.GZip or RequestFilters.GunZip. Exploitable by any unauthenticated client. The vulnerability was introduced on 2017-08-01 (commit 2618fe08f9) and was present for ~9 years.
Patches
| Line | Fixed in | Edition |
|---|---|---|
| v6.x (Community) | 6.49.0.0 | Community |
| v5.x (LTS) | 5.42.0.0 | Enterprise — contact enterprise@http4k.org |
| v4.x (LTS) | 4.51.0.0 | Enterprise — contact enterprise@http4k.org |
The fix caps decompression at 10MB by default; oversized requests through ServerFilters.GZip / RequestFilters.GunZip now return 413 Request Entity Too Large, and decompressing elsewhere throws SizeLimitExceededException. The keyed hmacSHA256 helper and other safe paths are unaffected.
Workarounds
For deployments that cannot upgrade immediately:
- Replace the
GZip/GunZipfilters with custom versions that wrap the decompressedInputStreamin a size-limited reader, or - Strip gzip-encoded request support at the edge (CDN, reverse proxy, or load balancer).
References
- Vulnerability introduced:
2618fe08f9 - Fix release: v6.49.0.0
- Background: CWE-409 — Improper Handling of Highly Compressed Data
Software afectado
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| Plataforma | Paquete | Versiones vulnerables | Corregida en |
|---|---|---|---|
| Java / Kotlin (Maven) | org.http4k:http4k-core | >= 6.0.0.0, < 6.49.0.0, >= 5.0.0.0, < 5.42.0.0, <= 4.48.2.0 | 6.49.0.0, 5.42.0.0 |
Referencias
- Vector CVSS
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- Debilidad (CWE)
CWE-409- Plataforma
- Java / Kotlin (Maven)
- Paquete
org.http4k:http4k-core- Publicada
- 17.08.2026
- Actualizado
- 11.10.2026 12:22
Fuentes y licencias
OSV / GitHub Advisory Database - GHSA-g4w2-6h2r-3m3w - CC BY 4.0
Historial de vulnerabilidades: org.http4k:http4k-core
Todas las vulnerabilidades publicadas de este paquete (Java / Kotlin (Maven)), de la más reciente a la más antigua. Muestra si es un fallo aislado o un paquete que hay que vigilar.
- Entradas en total
- 4
- Primera → última
- 06.2026 08.2026
- Sin corrección
- 0
- Explotada en ataques
- 0
Distribución por gravedad
- Alta 2
- Media 2
Divulgaciones por año
- 2026: 4
-
http4k: Unbounded gzip decompression in `ServerFilters.GZip` / `RequestFilters.GunZip` allowed memory-exhaustion DoS esta entrada
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