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ALPINE-CVE-2026-42533

ALPINE-CVE-2026-42533

This page contains facts from public vulnerability sources. Check the original advisory before updating.

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their control can exploit this vulnerability by sending crafted HTTP requests. This may cause a heap buffer overflow in the NGINX worker process leading to a restart. Additionally, attackers can execute code on systems with Address Space Layout Randomization (ASLR) disabled or when the attacker can bypass ASLR. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. 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 9.2 · Critical · Fix available

Published
Updated

Stack: system · web

Affected products and versions

  • nginx Alpine:v3.21

    Affected ranges
    • ECOSYSTEM: < 1.26.3-r2

    Update to 1.26.3-r2

  • nginx Alpine:v3.22

    Affected ranges
    • ECOSYSTEM: < 1.28.3-r6

    Update to 1.28.3-r6

  • nginx Alpine:v3.23

    Affected ranges
    • ECOSYSTEM: < 1.28.3-r6

    Update to 1.28.3-r6

  • nginx Alpine:v3.24

    Affected ranges
    • ECOSYSTEM: < 1.30.4-r0

    Update to 1.30.4-r0

Original sources

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