CVE-2026-42945

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, for systems with Address Space Layout Randomization (ASLR ) disabled, code execution is possible. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

CVSS Details

CVSS Score

8.1

Severity

HIGH

CVSS Vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Configurations (Affected Products)

No configuration data available.

NGINX Plus (受影响版本)

NGINX Open Source (受影响版本)

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# Vulnerable Nginx Configuration Example
server {
    listen 80;
    server_name localhost;

    location / {
        # Condition 1: Rewrite directive with capture ($1) and question mark (?)
        rewrite ^(.*)$ /target.php?id=$1;
        
        # Condition 2: Followed by a 'set' directive
        set $new_var $1;
        
        # Result: This combination triggers the heap buffer overflow
        return 200 "OK";
    }
}

# Attack Request (using curl)
# curl -I http://localhost/

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2026-42945
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2026-42945
[3] CVE Details https://www.cvedetails.com/cve/CVE-2026-42945/
[4] VulDB https://vuldb.com/cve/CVE-2026-42945
[5] https://my.f5.com/manage/s/article/K000161019
[6] https://depthfirst.com/nginx-rift
[7] https://github.com/DepthFirstDisclosures/Nginx-Rift

Raw JSON Data

JSON

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