Use After Free Affecting nginx package, versions <1.26.3-r2


Severity

Recommended
0.0
medium
0
10

Snyk's Security Team recommends NVD's CVSS assessment. Learn more

Threat Intelligence

EPSS
0.45% (37th percentile)

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  • Snyk IDSNYK-ALPINE321-NGINX-18025261
  • published21 Jul 2026
  • disclosed15 Jul 2026

Introduced: 15 Jul 2026

CVE-2026-56434  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade Alpine:3.21 nginx to version 1.26.3-r2 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream nginx package and not the nginx package as distributed by Alpine. See How to fix? for Alpine:3.21 relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1