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NGINX Plus and NGINX Open Source CVE-2026-42945

| EUVD-2026-30010 CRITICAL
Heap-based Buffer Overflow (CWE-122)
2026-05-13 f5 GHSA-gcgv-v5gf-c543
9.2
CVSS 4.0
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CVSS VectorNVD

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 Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

6
Analysis Updated
May 13, 2026 - 16:27 vuln.today
v2 (cvss_changed)
Re-analysis Queued
May 13, 2026 - 16:22 vuln.today
cvss_changed
Severity Changed
May 13, 2026 - 16:22 NVD
HIGH CRITICAL
CVSS changed
May 13, 2026 - 16:22 NVD
8.1 (HIGH) 9.2 (CRITICAL)
Analysis Generated
May 13, 2026 - 15:51 vuln.today
CVE Published
May 13, 2026 - 14:12 nvd
HIGH 8.1

DescriptionNVD

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, for systems with Address Space Layout Randomization (ASLR ) disabled, code execution is possible.  Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

AnalysisAI

Heap buffer overflow in NGINX Plus and NGINX Open Source ngx_http_rewrite_module allows remote attackers to crash worker processes and potentially execute code on systems without ASLR. The vulnerability requires specific rewrite directive configurations using PCRE captures with question marks in replacement strings, combined with attacker-crafted HTTP requests and conditions beyond the attacker's control. …

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RemediationAI

Within 24 hours: Identify all NGINX Plus and Open Source instances in your environment and audit rewrite directive configurations, particularly those using PCRE captures with question marks in replacement strings. Within 7 days: Apply the vendor-released patch from F5 to all affected NGINX instances; test patches in staging environments first. …

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Vendor StatusVendor

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CVE-2026-42945 vulnerability details – vuln.today

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