Use-After-Free in Nginx Gateway Fabric (CVE-2026-56434)
Summary
Vulnerability in Nginx Gateway Fabric (CVE-2026-56434). Risk of unauthorized operations or information disclosure.
Original description
The description as published by the source.
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_ssi_module module. This vulnerability may exist when the Server-Side Includes (SSI), proxy_pass, and proxy_buffering off directives are configured. With this configuration, an unauthenticated attacker with man-in-the-middle (MITM) ability to control responses from an upstream server may be able to cause a use-after-free in the NGINX worker process. This issue may lead to limited modification of memory or a restart of the NGINX worker process.
Impact:
This vulnerability may allow remote attackers to have limited control to modify memory contents or restart the NGINX worker process. There is no control plane exposure; this is a data plane issue only.
Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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-2026-56434 has been found in Nginx Gateway Fabric.
Risk of unauthorized operations or information disclosure. CVSS score: 6.5/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Nginx Gateway Fabric CVE-2026-56434" on the vendor's site.
CVE-2026-56434 (Nginx Gateway Fabric) — CWE-416 / CVSS v3 6.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
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.
Use-after-free (CWE-416) exists in Nginx Gateway Fabric.
Check the vendor advisory for the affected versions of Nginx Gateway Fabric.
Severity: Medium (CVSS 6.5/10). Risk of unauthorized operations or information disclosure.
Update to the patched release per vendor advisory.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
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
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1Identify exposure identify
Audit SBOM/dependencies for affected components.資産台帳・SBOM・依存マニフェストで Nginx Gateway Fabric を使っているサービスとバージョンを洗い出す。
-
2Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Alpine Linux ALPINE-CVE-2026-56434 nginx Fixed in: 1.26.3-r2
- BellSoft Alpaquita BELL-CVE-2026-56434 nginx Fixed in: 1.30.4-r1
- Debian DEBIAN-CVE-2026-56434 nginx Fixed in: 1.22.1-9+deb12u10
- Ubuntu UBUNTU-CVE-2026-56434 nginx
References
- advisory my.f5.com
- web nvd.nist.gov
- web github.com