# CVE-2026-42945

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.

- Page: https://www.vulneraibility.com/cve/CVE-2026-42945
- CVSS: 8.1
- Known exploited: not in CISA KEV as of our last sync
- EPSS: 68.05% (percentile 99.3)
- Unvetted proof-of-concept code on GitHub: 48 GitHub proofs of concept (first 2026-05-14)
- CISA SSVC: exploitation none, automatable no, technical impact total (assessed 2026-05-13)
- Weakness: CWE-122, CWE-131
- Published: 2026-05-13

## Affected versions

- F5 NGINX Open Source: affected >= 0.6.27 and < 1.30.1; fixed in >= 1.31.0 and < *
- F5 NGINX Plus: affected >= R36 and < R36 P4; >= R32 and < R32 P6; fixed in >= R37 and < *

A version outside these ranges is not a statement that it is unaffected.

## References

- [patch] https://my.f5.com/manage/s/article/K000161019
- [other] https://depthfirst.com/nginx-rift
- [other] https://github.com/DepthFirstDisclosures/Nginx-Rift
- [other] https://access.redhat.com/security/cve/CVE-2026-42945
- [other] https://bugzilla.redhat.com/show_bug.cgi?id=2477116
- [other] https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42945.json
- [advisory] https://access.redhat.com/errata/RHSA-2026:17790
- [advisory] https://access.redhat.com/errata/RHSA-2026:18063
- [advisory] https://access.redhat.com/errata/RHSA-2026:19159
- [advisory] https://access.redhat.com/errata/RHSA-2026:18041
- [advisory] https://access.redhat.com/errata/RHSA-2026:17791
- [advisory] https://access.redhat.com/errata/RHSA-2026:17751
- [advisory] https://access.redhat.com/errata/RHSA-2026:17792
- [advisory] https://access.redhat.com/errata/RHSA-2026:17793
- [advisory] https://access.redhat.com/errata/RHSA-2026:17752
- [advisory] https://access.redhat.com/errata/RHSA-2026:17794
- [advisory] https://access.redhat.com/errata/RHSA-2026:17753
- [advisory] https://access.redhat.com/errata/RHSA-2026:18029
- [advisory] https://access.redhat.com/errata/RHSA-2026:19371
- [advisory] https://access.redhat.com/errata/RHSA-2026:19374
- [advisory] https://access.redhat.com/errata/RHSA-2026:19372
- [advisory] https://access.redhat.com/errata/RHSA-2026:17417
- [advisory] https://access.redhat.com/errata/RHSA-2026:22396
- [advisory] https://access.redhat.com/errata/RHSA-2026:22393
- [advisory] https://access.redhat.com/errata/RHSA-2026:22394
- [advisory] https://access.redhat.com/errata/RHSA-2026:22390
- [advisory] https://access.redhat.com/errata/RHSA-2026:22388
- [advisory] https://access.redhat.com/errata/RHSA-2026:22389
- [advisory] https://access.redhat.com/errata/RHSA-2026:22383
- [advisory] https://access.redhat.com/errata/RHSA-2026:22382
- [advisory] https://access.redhat.com/errata/RHSA-2026:20442
- [advisory] https://access.redhat.com/errata/RHSA-2026:20444
- [advisory] https://access.redhat.com/errata/RHSA-2026:58981
- [advisory] https://access.redhat.com/errata/RHSA-2026:21275

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Summary, impact and action are written by the vulneraibility.com AI analysis pipeline from the CVE record, NVD, CISA and FIRST data; verify against the references.