CVE-2026-42945

CVE Details

Release Date:	2026-05-13
Impact:	Critical	What is this?

Description

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, for systems with Address Space Layout Randomization (ASLR ) disabled, code execution is possible. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

See more information about CVE-2026-42945 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	8.1
Vector String:	CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Version:	3.1
Attack Vector:	Network
Attack Complexity:	High
Privileges Required:	None
User Interaction:	None
Scope:	Unchanged
Confidentiality Impact:	High
Integrity Impact:	High
Availability Impact:	High

Errata information

Platform	Errata	Release Date
Oracle Linux version 10 (nginx)	ELSA-2026-18063	2026-05-19
Oracle Linux version 8 (nginx)	ELSA-2026-18041	2026-05-19
Oracle Linux version 9 (nginx)	ELSA-2026-18029	2026-05-19