CVE-2026-42945
NGINX ngx_http_rewrite_module vulnerability
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.
How to fix CVE-2026-42945
To remediate CVE-2026-42945, upgrade the affected package to a fixed version below.
- —upgrade to 1.28.3-r1 or later
- —upgrade to 1.30.1 or later
- —upgrade to 1.30.1 or later
- —upgrade to 1.18.0-6.1+deb11u6 or later
Is CVE-2026-42945 being exploited?
Low — EPSS is 0.9%, meaning exploitation activity has not been observed at scale.
Affected packages (4)
- from 0, < 1.28.3-r1
- >= 0.6.27, < 1.30.1
- >= 0.6.27, < 1.30.1
- from 0, < 1.18.0-6.1+deb11u6
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |