CVE-2026-42945

critical

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, 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.

References

https://my.f5.com/manage/s/article/K000161019

https://hackread.com/hackers-exploit-nginx-rift-vulnerability-nginx-f5-products/

https://www.theregister.com/security/2026/05/18/nginx-rift-attackers-waste-no-time-targeting-exposed-servers/5241851

https://thehackernews.com/2026/05/nginx-cve-2026-42945-exploited-in-wild.html

https://www.securityweek.com/f5-patches-over-50-vulnerabilities/

https://www.bleepingcomputer.com/news/security/18-year-old-nginx-vulnerability-allows-dos-potential-rce/

https://thehackernews.com/2026/05/18-year-old-nginx-rewrite-module-flaw.html

https://securityaffairs.com/192132/hacking/nginx-rift-an-18-year-old-flaw-in-the-worlds-most-deployed-web-server-just-came-to-light.html

https://depthfirst.com/nginx-rift

https://github.com/DepthFirstDisclosures/Nginx-Rift

Details

Source: Mitre, NVD

Published: 2026-05-13

Updated: 2026-05-21

Named Vulnerability: NGINX Rift

Risk Information

CVSS v2

Base Score: 9

Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:C

Severity: High

CVSS v3

Base Score: 8.1

Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Severity: High

CVSS v4

Base Score: 9.2

Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Severity: Critical

EPSS

EPSS: 0.00166

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Interest

Detections

Analytics