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CVE-2026-53659 high CVSS 7.5

Vulnerability in org.http4k:http4k-core (CVE-2026-53659)

Summary

Vulnerability in org.http4k:http4k-core (CVE-2026-53659). Risk of unauthorized operations or information disclosure. Exploitable via ServerFilters.GZip. Mitigation: upgrade to 6.49.0.0 or later.

Original description

The description as published by the source.

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 / GunZip filters with custom versions that wrap the decompressed InputStream in a size-limited reader, or
  • Strip gzip-encoded request support at the edge (CD…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-53659 has been found in org.http4k:http4k-core.
Attackers can target a specific entry point like ServerFilters.GZip over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade org.http4k:http4k-core to 6.49.0.0 or later.
If unsure, ask your IT team or search "org.http4k:http4k-core CVE-2026-53659" on the vendor's site.

CVE-2026-53659 (org.http4k:http4k-core) — CWE-409 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: ServerFilters.GZip / RequestFilters.GunZip / Gzip / SizeLimitExceededException
Patched: 6.49.0.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (CWE-409) exists in org.http4k:http4k-core. Attackers reach the vulnerable code path via ServerFilters.GZip without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of org.http4k:http4k-core. Attack surface: ServerFilters.GZip / RequestFilters.GunZip / Gzip / SizeLimitExceededException.

🔥 Severity

Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 6.49.0.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Audit SBOM/dependencies to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify exposure identify 
    Audit SBOM/dependencies for affected components.

    資産台帳・SBOM・依存マニフェストで org.http4k:http4k-core を使っているサービスとバージョンを洗い出す。

  2. 2
    Apply patch patch 
    Upgrade org.http4k:http4k-core to 6.49.0.0

    ステージング環境で 6.49.0.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。

  3. 3
    Post-deployment verification verify 
    Confirm patched version is live in production

    パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

maven org.http4k:http4k-core
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"4.48.2.0"}]}]

References

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