CVE DATABASE / CVE-2026-42945
CVE-2026-42945
Summary
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.
CVSS 3.1 breakdown
| Base score | 8.1 (HIGH) |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| Attack vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | NONE |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | HIGH |
| Integrity | HIGH |
| Availability | HIGH |
Weakness type (CWE)
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Our coverage
- Chrome 148 Patches 151 Vulnerabilities Including 22 Critical RCE Flaws
- CVE-2026-40933: Flowise Critical RCE, Exploit Code Now Public
- CVE-2026-42945: 18-Year NGINX Heap Flaw Enables Unauthenticated RCE
References
- https://my.f5.com/manage/s/article/K000161019
- https://depthfirst.com/nginx-rift
- https://github.com/DepthFirstDisclosures/Nginx-Rift
Data: NIST NVD. NVD last modified 2026-05-21. Always verify against the vendor advisory before acting.