What is 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.
The record classifies CVE-2026-42945 under weakness class CWE-122. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 2 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 167 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 8.1 — HIGH
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS v4.0 base score
- 9.2
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 - EPSS (FIRST)
- 3.3% probability of exploitation in the next 30 days, higher than 88.5% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 9.6/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-05-13, last modified 2026-09-10
Is CVE-2026-42945 being exploited?
Weaponised exploit code for CVE-2026-42945 is publicly available. 11 public proof-of-concept repositories are tracked for this identifier. It currently carries a trending score of 35 in the Threadlinqs vulnerability feed.
- cipherspy/CVE-2026-42945-POC (github)
- friparia/NGINX_RIFT_SCAN_CVE_2026_42945 (github)
- MateusVerass/nGixshell (github)
- rheodev/CVE-2026-42945 (github)
- oseasfr/Scanner_CVE_2026-42945 (github)
- p3Nt3st3r-sTAr/CVE-2026-42945-POC (github)
- nu0l/NGINX-Rift (github)
- iammerrida-source/nginx-rift-detect (github)
Affected products and versions
- F5: NGINX Plus, NGINX Open Source
How to fix CVE-2026-42945
No vendor patch reference has been recorded for CVE-2026-42945 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-42945
3 tracked threats in the Threadlinqs corpus reference CVE-2026-42945, either in the campaign’s CVE list or as an indicator on the campaign record.
- F5 Patches Multiple NGINX Vulnerabilities: Heap Overflow, Memory Disclosure, and Use-After-Free (CVE-2026-42533, CVE-2026-60005, CVE-2026-56434) — CRITICAL · 2026-07-15
- Nginx-poolslip CVE-2026-9256 — Pre-Auth Heap Buffer Overflow in NGINX ngx_http_rewrite_module (Patch Bypass of CVE-2026-42945 'NGINX Rift') — CRITICAL · 2026-05-23
- NGINX Rift — CVE-2026-42945 Heap Buffer Overflow in ngx_http_rewrite_module (CVSS v4 9.2 Critical, 18-Year-Old Pre-Auth RCE, Public PoC) — CRITICAL · 2026-05-14
Sources
Enriched from CVE.org, FIRST EPSS, public proof-of-concept repositories. Last verified by Threadlinqs on .