CVE-2026-42945
Description
A flaw was found in NGINX, specifically within the ngx_http_rewrite_module. An unauthenticated attacker can exploit this vulnerability by sending crafted HTTP requests under specific rewrite configurations. This can lead to a heap buffer overflow in the NGINX worker process, which may result in arbitrary code execution if Address Space Layout Randomization (ASLR), a security technique to prevent exploitation, is disabled. Otherwise, this flaw causes a denial of service due to a restart of the NGINX worker process.
Statement
Critical: This flaw in NGINX's ngx_http_rewrite_module can lead to arbitrary code execution due to a heap buffer overflow if Address Space Layout Randomization (ASLR) is disabled, or a denial of service otherwise. Exploitation requires specific, non-default NGINX rewrite configurations involving unnamed PCRE captures and a question mark in the replacement string.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | High |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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