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Vulnerabilities CVE-2026-42533

CVE-2026-42533

High
Open
TLP:CLEAR

NGINX Map directive and Regex matching vulnerability

NVD CVE.org
Critical Infrastructure

AI Analysis

No AI analysis yet.

Description

A vulnerability exists in NGINX Plus and NGINX Open Source when a map directive uses regex matching and a string expression references the map's regex capture variables before referencing the map output variable. Alternatively, the same result could be achieved by using a non-cacheable variable in a string expression under certain conditions. An unauthenticated attacker along with conditions beyond their 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. Impact: This vulnerability may allow remote attackers to cause a denial-of-service (DoS) on the NGINX system or to possibly trigger a code execution. There is no control plane exposure; this is a data plane issue only.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Details

CVSS Score
8.1
EPSS Score
3.51%

88.1th percentile

CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Confidence
90%
Published
Jul 15, 2026
Last Modified
Jul 29, 2026
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