CVE-2026-42945

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. High risk of data exposure, data tampering, service disruption.

Exploit odds

68.0% chance of exploitation in the next 30 days (EPSS). Higher than most.

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-04-30 23:04 UTC ReservedThe CVE id was reserved by its CNA
2. 2026-05-13 16:16 UTC PublishedDisclosed publicly on CVE.org and NVD
3. 2026-10-26 14:10 UTC Last updatedMost recent change to the record

Details

Published

2026-05-13 16:16 UTC

Last modified

2026-10-26 14:10 UTC

Exploit probability

68.0% · EPSS, next 30 days

Weakness

CWE-122

Record status

Modified

Affected

• f5 Dos ≤ 4.7.0
• f5 Dos 4.8.0
• f5 nginx Gateway Fabric ≤ 1.6.2
• f5 nginx Gateway Fabric ≤ 2.5.1
• f5 nginx Ingress Controller ≤ 3.7.2
• f5 nginx Ingress Controller ≤ 4.0.1
• f5 nginx Ingress Controller ≤ 5.4.1
• f5 nginx Instance Manager ≤ 2.21.1

Attack profile CVSS 4.0 · 9.2

Attack vector

Network

Complexity

High

Attack requirements

None

Privileges needed

None

User interaction

None

Confidentiality

High

Integrity

High

Availability

High