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8.1highHigh

CVE-2026-42945

F5 Dos

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when the rewrite directive is followed by a rewrite, if, or set directive and an unnamed Perl-Compatible Regular Expression (PCRE) capture (for example, $1, $2) with a replacement string that includes a question mark (?). An unauthenticated attacker along with conditions beyond its 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. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Exploitation status

  • Published references include exploit or proof-of-concept material. There is no confirmation it is being used in real attacks.
  • A vendor advisory or patch reference has been published.

What the metrics mean

  • It is reachable over a network, without needing local access.
  • For an attacker who can reach it, exploitation depends on conditions outside the attacker's control.
  • To exploit it, no account is needed.
  • Beyond that, no action by a user is required.

Scoring

CVSS
8.1 (v3.1)
Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS v4
9.2
Weakness
CWE-122
Assigned by
f5sirt@f5.com

Dates

Published
2026-05-13
Last modified
2026-08-25
Sources
NVD

Affected products

  • F5 Dos4.3.0 - 4.7.0, 4.8.0
  • F5 Nginx Gateway Fabric1.3.0 - 1.6.2, 2.0.0 - 2.5.1
  • F5 Nginx Ingress Controller3.5.0 - 3.7.2, 4.0.0 - 4.0.1, 5.0.0 - 5.4.1
  • F5 Nginx Instance Manager2.16.0 - 2.21.1
  • F5 Nginx Open Source0.6.27 - 1.30.0
  • F5 Nginx Plusr32 - r36
  • F5 Waf4.9.0 - 4.16.0, 5.1.0 - 5.8.0, 5.9.0 - 5.12.1

As listed in the NVD configuration data. Not a statement about your estate.

References