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CVE-2026-42533

CVE-2026-42533 · NGINX Map directive and Regex matching vulnerability

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 · EPSS 0.9% · Public exploit · Fix available

Published
Updated

Stack: system · web

Affected products and versions

  • nginx plus

    Versions
    • ≥ 37.0.0.1, < 37.0.3.1: Affected (custom)
    • ≥ R36, < R36 P7: Affected (custom)
    • ≥ R33: Affected (custom)

    Update to 37.0.3.1

  • nginx

    Versions
    • ≥ 1.31.2, < 1.31.3: Affected (custom)
    • ≥ 0.9.6, < 1.30.4: Affected (custom)

    Update to 1.30.4; Update to 1.31.3

  • nginx Debian:12

    Versions
    • 1.22.1-9
    • 1.22.1-9+deb12u1
    • 1.22.1-9+deb12u2
    • 1.22.1-9+deb12u3
    • 1.22.1-9+deb12u4
    • 1.22.1-9+deb12u5
    • 1.22.1-9+deb12u6
    • 1.22.1-9+deb12u7
    • 1.22.1-9+deb12u8
    • 1.22.1-9+deb12u9
    Affected ranges
    • ECOSYSTEM: < 1.22.1-9+deb12u10

    Update to 1.22.1-9+deb12u10

  • nginx Debian:13

    Versions
    • 1.26.3-3
    • 1.26.3-3+deb13u1
    • 1.26.3-3+deb13u2
    • 1.26.3-3+deb13u3
    • 1.26.3-3+deb13u4
    • 1.26.3-3+deb13u5
    • 1.26.3-3+deb13u6
    • 1.26.3-3+deb13u7
    Affected ranges
    • ECOSYSTEM: < 1.26.3-3+deb13u8

    Update to 1.26.3-3+deb13u8

  • nginx Debian:14

    Versions
    • 1.26.3-3
    • 1.28.0-1
    • 1.28.0-2
    • 1.28.0-3
    • 1.28.0-4
    • 1.28.0-5
    • 1.28.0-6
    • 1.28.1-1
    • 1.28.1-2
    • 1.28.1-3
    • 1.28.2-1
    • 1.28.2-2
    • 1.28.2-3
    • 1.28.2-4
    • 1.28.3-1
    • 1.28.3-2
    • 1.30.0-1
    • 1.30.0-2
    • 1.30.0-3
    • 1.30.0-4
    • 1.30.1-1
    • 1.30.1-2
    • 1.30.1-3
    • 1.30.1-4
    • 1.30.1-5
    • 1.30.1-6
    • 1.30.1-7
    • 1.30.4-1
    • 1.30.4-2
    Affected ranges
    • ECOSYSTEM: < 1.30.4-3

    Update to 1.30.4-3

  • nginx Ubuntu:Pro:14.04:LTS

    Versions
    • 1.4.1-3ubuntu1
    • 1.4.3-2ubuntu1
    • 1.4.4-1ubuntu1
    • 1.4.4-2ubuntu1
    • 1.4.4-4ubuntu1
    • 1.4.5-1ubuntu1
    • 1.4.6-1ubuntu2
    • 1.4.6-1ubuntu3
    • 1.4.6-1ubuntu3.1
    • 1.4.6-1ubuntu3.2
    • 1.4.6-1ubuntu3.3
    • 1.4.6-1ubuntu3.4
    • 1.4.6-1ubuntu3.5
    • 1.4.6-1ubuntu3.6
    • 1.4.6-1ubuntu3.7
    • 1.4.6-1ubuntu3.8
    • 1.4.6-1ubuntu3.9
    • 1.4.6-1ubuntu3.9+esm1
    • 1.4.6-1ubuntu3.9+esm2
    • 1.4.6-1ubuntu3.9+esm3
    • 1.4.6-1ubuntu3.9+esm4
    • 1.4.6-1ubuntu3.9+esm5
    • 1.4.6-1ubuntu3.9+esm6
    • 1.4.6-1ubuntu3.9+esm8
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • nginx Ubuntu:Pro:16.04:LTS

    Versions
    • 1.9.3-1ubuntu1
    • 1.9.6-2ubuntu1
    • 1.9.6-2ubuntu2
    • 1.9.9-0ubuntu1
    • 1.9.9-1ubuntu1
    • 1.9.10-0ubuntu1
    • 1.9.10-1ubuntu1
    • 1.9.11-0ubuntu1
    • 1.9.11-0ubuntu2
    • 1.9.12-0ubuntu1
    • 1.9.13-0ubuntu1
    • 1.9.14-0ubuntu1
    • 1.9.15-0ubuntu1
    • 1.10.0-0ubuntu0.16.04.1
    • 1.10.0-0ubuntu0.16.04.2
    • 1.10.0-0ubuntu0.16.04.3
    • 1.10.0-0ubuntu0.16.04.4
    • 1.10.3-0ubuntu0.16.04.1
    • 1.10.3-0ubuntu0.16.04.2
    • 1.10.3-0ubuntu0.16.04.3
    • 1.10.3-0ubuntu0.16.04.4
    • 1.10.3-0ubuntu0.16.04.5
    • 1.10.3-0ubuntu0.16.04.5+esm1
    • 1.10.3-0ubuntu0.16.04.5+esm2
    • 1.10.3-0ubuntu0.16.04.5+esm3
    • 1.10.3-0ubuntu0.16.04.5+esm4
    • 1.10.3-0ubuntu0.16.04.5+esm5
    • 1.10.3-0ubuntu0.16.04.5+esm6
    • 1.10.3-0ubuntu0.16.04.5+esm7
    • 1.10.3-0ubuntu0.16.04.5+esm9
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • nginx Ubuntu:Pro:18.04:LTS

    Versions
    • 1.12.1-0ubuntu2
    • 1.13.6-2ubuntu1
    • 1.13.6-2ubuntu2
    • 1.13.10-1ubuntu1
    • 1.13.12-0ubuntu1
    • 1.14.0-0ubuntu1
    • 1.14.0-0ubuntu1.1
    • 1.14.0-0ubuntu1.2
    • 1.14.0-0ubuntu1.3
    • 1.14.0-0ubuntu1.4
    • 1.14.0-0ubuntu1.5
    • 1.14.0-0ubuntu1.6
    • 1.14.0-0ubuntu1.7
    • 1.14.0-0ubuntu1.9
    • 1.14.0-0ubuntu1.10
    • 1.14.0-0ubuntu1.11
    • 1.14.0-0ubuntu1.11+esm1
    • 1.14.0-0ubuntu1.11+esm2
    • 1.14.0-0ubuntu1.11+esm4
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • nginx Ubuntu:Pro:20.04:LTS

    Versions
    • 1.16.1-0ubuntu2
    • 1.16.1-0ubuntu3
    • 1.17.5-0ubuntu1
    • 1.17.6-0ubuntu1
    • 1.17.7-0ubuntu1
    • 1.17.8-0ubuntu1
    • 1.17.8-0ubuntu2
    • 1.17.8-0ubuntu3
    • 1.17.9-0ubuntu1
    • 1.17.9-0ubuntu2
    • 1.17.9-0ubuntu3
    • 1.17.10-0ubuntu1
    • 1.18.0-0ubuntu1
    • 1.18.0-0ubuntu1.2
    • 1.18.0-0ubuntu1.3
    • 1.18.0-0ubuntu1.4
    • 1.18.0-0ubuntu1.5
    • 1.18.0-0ubuntu1.6
    • 1.18.0-0ubuntu1.7
    • 1.18.0-0ubuntu1.7+esm1
    • 1.18.0-0ubuntu1.7+esm3
    Affected ranges
    • ECOSYSTEM: (−∞, +∞)

    No fix published

  • nginx Ubuntu:22.04:LTS

    Versions
    • 1.18.0-6ubuntu11
    • 1.18.0-6ubuntu12
    • 1.18.0-6ubuntu14
    • 1.18.0-6ubuntu14.1
    • 1.18.0-6ubuntu14.2
    • 1.18.0-6ubuntu14.3
    • 1.18.0-6ubuntu14.4
    • 1.18.0-6ubuntu14.5
    • 1.18.0-6ubuntu14.6
    • 1.18.0-6ubuntu14.7
    • 1.18.0-6ubuntu14.8
    • 1.18.0-6ubuntu14.10
    • 1.18.0-6ubuntu14.11
    • 1.18.0-6ubuntu14.12
    • 1.18.0-6ubuntu14.13
    • 1.18.0-6ubuntu14.14
    • 1.18.0-6ubuntu14.15
    • 1.18.0-6ubuntu14.16
    • 1.18.0-6ubuntu14.17
    • 1.18.0-6ubuntu14.18
    • 1.18.0-6ubuntu14.19
    • 1.18.0-6ubuntu14.20
    Affected ranges
    • ECOSYSTEM: < 1.18.0-6ubuntu14.21

    Update to 1.18.0-6ubuntu14.21

  • nginx Ubuntu:24.04:LTS

    Versions
    • 1.24.0-1ubuntu1
    • 1.24.0-2ubuntu1
    • 1.24.0-2ubuntu2
    • 1.24.0-2ubuntu3
    • 1.24.0-2ubuntu4
    • 1.24.0-2ubuntu6
    • 1.24.0-2ubuntu7
    • 1.24.0-2ubuntu7.1
    • 1.24.0-2ubuntu7.3
    • 1.24.0-2ubuntu7.4
    • 1.24.0-2ubuntu7.5
    • 1.24.0-2ubuntu7.6
    • 1.24.0-2ubuntu7.7
    • 1.24.0-2ubuntu7.8
    • 1.24.0-2ubuntu7.9
    • 1.24.0-2ubuntu7.10
    • 1.24.0-2ubuntu7.11
    • 1.24.0-2ubuntu7.12
    • 1.24.0-2ubuntu7.13
    • 1.24.0-2ubuntu7.14
    • 1.24.0-2ubuntu7.15
    • 1.24.0-2ubuntu7.16
    • 1.24.0-2ubuntu7.17
    Affected ranges
    • ECOSYSTEM: < 1.24.0-2ubuntu7.18

    Update to 1.24.0-2ubuntu7.18

  • nginx Ubuntu:26.04:LTS

    Versions
    • 1.28.0-6ubuntu1
    • 1.28.1-2ubuntu1
    • 1.28.1-3ubuntu1
    • 1.28.2-2ubuntu1
    • 1.28.3-2ubuntu1
    • 1.28.3-2ubuntu1.1
    • 1.28.3-2ubuntu1.2
    • 1.28.3-2ubuntu1.3
    • 1.28.3-2ubuntu1.4
    • 1.28.3-2ubuntu1.5
    • 1.28.3-2ubuntu1.6
    • 1.28.3-2ubuntu1.7
    • 1.28.3-2ubuntu1.8
    • 1.28.3-2ubuntu1.9
    • 1.28.3-2ubuntu1.10
    Affected ranges
    • ECOSYSTEM: < 1.28.3-2ubuntu1.11

    Update to 1.28.3-2ubuntu1.11

Original sources

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