Instituto Nacional de ciberseguridad. Sección Incibe
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CVE-2026-42055

Severity CVSS v4.0:
CRITICAL
Type:
CWE-122 Heap-based Buffer Overflow
Publication date:
17/06/2026
Last modified:
28/07/2026

Description

NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_proxy_v2_module and ngx_http_grpc_module modules. This vulnerability exists when the proxy_http_version to 2 or grpc_pass directives are used to proxy HTTP/2 traffic, the ignore_invalid_headers directive is set to off, and the large_client_header_buffers directive size is larger than 2 megabytes. A remote, unauthenticated attacker, along with conditions beyond their control, could send large headers while creating an upstream request. This may cause a heap-based 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 /> <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:P/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:P/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): Present
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:dos:4.9.0:*:*:*:*:nginx:*:*
cpe:2.3:a:f5:nginx_app_protect_dos:*:*:*:*:*:*:*:* 4.3.0 (including) 4.7.0 (including)
cpe:2.3:a:f5:nginx_app_protect_waf:*:*:*:*:*:*:*:* 4.10.0 (including) 4.16.0 (including)
cpe:2.3:a:f5:nginx_app_protect_waf:*:*:*:*:*:*:*:* 5.2.0 (including) 5.8.0 (including)
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) 2.6.4 (excluding)
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:* 3.5.0 (including) 3.7.2 (including)
cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:* 5.0.0 (including) 5.5.1 (excluding)
cpe:2.3:a:f5:nginx_ingress_controller:4.0.0:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_ingress_controller:4.0.1:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:* 2.17.0 (including) 2.22.0 (including)
cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:* 1.30.0 (including) 1.30.3 (excluding)
cpe:2.3:a:f5:nginx_open_source:1.31.1:*:*:*:*:*:*:*
cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:* 37.0.0 (including) 37.0.1 (including)
cpe:2.3:a:f5:nginx_plus:r3:*:*:*:*:*:*:*

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


References to Advisories, Solutions, and Tools