IM
IronMonkey Threat Research

CVE-2026-42945 CRITICAL

Published: 2026-05-13 | Last Modified: 2026-06-27 | Status: Modified

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, 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.

CVSS Metrics

Base Score: 8.1 (HIGH)

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

Attack VectorNETWORK
Attack ComplexityHIGH
Privileges RequiredNONE
User InteractionNONE
ScopeUNCHANGED
Confidentiality ImpactHIGH
Integrity ImpactHIGH
Availability ImpactHIGH

Source: [email protected]

Type: Secondary

Exploitability Score: 2.2

Impact Score: 5.9

Base Score: 9.2 (CRITICAL)

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Attack VectorNETWORK
Attack ComplexityHIGH
Attack RequirementsNONE
Privileges RequiredNONE
User InteractionNONE
Vulnerability ConfidentialityHIGH
Vulnerability IntegrityHIGH
Vulnerability AvailabilityHIGH
Subsequent ConfidentialityNONE
Subsequent IntegrityNONE
Subsequent AvailabilityNONE

Source: [email protected]

Type: Secondary

Weaknesses

Source Type Description
[email protected] Primary
en CWE-122
0b0ca135-0b70-47e7-9f44-1890c2a1c46c Secondary
en CWE-131

Affected Products

Vendor Product Version Update Type
f5 dos * <built-in method update of dict object at 0x75d80224b9c0> Application
f5 dos 4.8.0 <built-in method update of dict object at 0x75d8039f3500> Application
f5 nginx_gateway_fabric * <built-in method update of dict object at 0x75d8039f3480> Application
f5 nginx_gateway_fabric * <built-in method update of dict object at 0x75d80224bec0> Application
f5 nginx_ingress_controller * <built-in method update of dict object at 0x75d802249540> Application
f5 nginx_ingress_controller * <built-in method update of dict object at 0x75d802249440> Application
f5 nginx_ingress_controller * <built-in method update of dict object at 0x75d8039f2680> Application
f5 nginx_instance_manager * <built-in method update of dict object at 0x75d8039f0740> Application
f5 nginx_open_source * <built-in method update of dict object at 0x75d8039f29c0> Application
f5 nginx_plus * <built-in method update of dict object at 0x75d80224b700> Application
f5 waf * <built-in method update of dict object at 0x75d828aadf40> Application
f5 waf * <built-in method update of dict object at 0x75d8039f0f80> Application
f5 waf * <built-in method update of dict object at 0x75d8039f0040> Application

Affected Configurations

Operator: OR

Vulnerable CPE
Yes cpe:2.3:a:f5:dos:*:*:*:*:*:nginx:*:*
Yes cpe:2.3:a:f5:dos:4.8.0:*:*:*:*:nginx:*:*
Yes cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_gateway_fabric:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_ingress_controller:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_instance_manager:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_open_source:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:nginx_plus:*:*:*:*:*:*:*:*
Yes cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
Yes cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*
Yes cpe:2.3:a:f5:waf:*:*:*:*:*:nginx:*:*

References

Notification
Message here