Instituto Nacional de ciberseguridad. Sección Incibe
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CVE-2026-42533

Severity CVSS v4.0:
CRITICAL
Type:
CWE-122 Heap-based Buffer Overflow
Publication date:
15/07/2026
Last modified:
10/08/2026

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&amp;#39;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.<br /> <br /> Impact:<br /> 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.<br /> <br /> <br /> <br /> <br />  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

Impact

Vector 4.0
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 CVSS v4.0 Severity and Metrics:

Base Score: 9.20 CRITICAL
Vector: 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

Attack Vector (AV): Network
Attack Complexity (AC): High
Attack Requirements (AT): None
Privileges Required (PR): None
User Interaction (UI): None
Confidentiality (VC): High
Integrity (VI): High
Availability (VA): High
Confidentiality (SC): None
Integrity (SI): None
Availability (SA): None

Base Score 4.0
9.20
Severity 4.0
CRITICAL
Vector 3.x
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H CVSS v3.1 Severity and Metrics:

Base Score: 8.10 HIGH
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector (AV): Network
Attack Complexity (AC): High
Privileges Required (PR): None
User Interaction (UI): None
Scope (S): Unchanged
Confidentiality (C): High
Integrity (I): High
Availability (A): High

Base Score 3.x
8.10
Severity 3.x
HIGH

Vulnerable products and versions

CPE From Up to
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* 1.3.0 (including) 1.6.2 (including)
cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:* 2.0.0 (including) 2.6.7 (excluding)
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* 3.5.0 (including) 3.7.2 (including)
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:continuous_releases:*:*:* 5.0.0 (including) 5.5.3 (excluding)
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:long-term_support:*:*:* 2026-lts-r1 (including) 2026-lts-r4 (excluding)
cpe:2.3:a:f5:nginx_ingress_controller:4.0.0:*:*:*:continuous_releases:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:4.0.1:*:*:*:continuous_releases:*:*:*
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* 37.0.0.1 (including) 37.0.3.1 (excluding)
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* r33 (including) r36 (excluding)
cpe:2.3:a:f5:nginx_plus:r36:-:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:p1:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:p2:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:p3:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:p4:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:r36:p5:*:*:*:*:*:*

To consult the complete list of CPE names with products and versions, see this page


References to Advisories, Solutions, and Tools