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CVE-2026-53659— http4k: Unbounded gzip decompression in `ServerFilters.GZip` / `RequestFilters.GunZip` allowed memory-exhaustion DoS

Quick assessment

Affected
http4k http4k
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

http4k是http4k团队开源的一个轻量级但功能齐全的 HTTP 工具包。 http4k 4.51.0.0之前版本、5.0.0.0至5.42.0.0之前版本和6.0.0.0至6.49.0.0之前版本存在资源管理错误漏洞，该漏洞源于ServerFilters.GZip、RequestFilters.GunZip及底层Gzip请求体解压功能未限制解压后大小，未经身份验证的攻击者可发送较小的gzip编码请求体解压为数GB数据，耗尽JVM堆内存并导致其他客户端拒绝服务。

CVSS 7.5 · High EPSS 0.44% · P37

Possible ATT&CK Techniques 2 AI

T1298 T1499 · Endpoint Denial of Service

Affected Version Matrix 3

VendorProduct Version RangeStatus
http4k http4k < 4.51.0.0 affected
>= 5.0.0.0, < 5.42.0.0 affected
>= 6.0.0.0, < 6.49.0.0 affected
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I. Basic Information for CVE-2026-53659

Vulnerability Information
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Vulnerability Title
http4k: Unbounded gzip decompression in `ServerFilters.GZip` / `RequestFilters.GunZip` allowed memory-exhaustion DoS
Source: CVE Program / CVE List V5
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对高度压缩数据的处理不恰当(数据放大攻击)
Source: CVE Program / CVE List V5
Vulnerability Title
http4k 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
http4k是http4k团队开源的一个轻量级但功能齐全的 HTTP 工具包。 http4k 4.51.0.0之前版本、5.0.0.0至5.42.0.0之前版本和6.0.0.0至6.49.0.0之前版本存在资源管理错误漏洞，该漏洞源于ServerFilters.GZip、RequestFilters.GunZip及底层Gzip请求体解压功能未限制解压后大小，未经身份验证的攻击者可发送较小的gzip编码请求体解压为数GB数据，耗尽JVM堆内存并导致其他客户端拒绝服务。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
http4k http4k < 4.51.0.0 -

II. Public POCs for CVE-2026-53659

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III. Intelligence Information for CVE-2026-53659

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Patches & Fixes for CVE-2026-53659 (1)

Vendor Advisories for CVE-2026-53659 (1)

Vendor Pages for CVE-2026-53659 (1)

IV. Related Vulnerabilities

Same product: http4k
Same vendor: http4k
Same weakness: CWE-409

V. Comments for CVE-2026-53659

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