Raw 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/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:XSummary
CVE-2026-42945 is a critical-severity Heap-based Buffer Overflow (CWE-122) vulnerability in F5 Nginx Ingress Controller. Its CVSS base score is 9.2 (Critical).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked in the top 0.8% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SA-11 (Developer Testing and Evaluation) and SI-10 (Information Input Validation) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
NGINX Plus and NGINX Open Source contain a vulnerability in the ngx_http_rewrite_module module that triggers when a rewrite directive is followed by another rewrite, if, or set directive using an unnamed PCRE capture such as $1 or $2 in a replacement string containing a question mark. The flaw is tracked as CVE-2026-42945, carries a CVSS 4.0 score of 9.2, and is classified under CWE-122 for heap-based buffer overflow.
An unauthenticated attacker can trigger the issue by sending specially crafted HTTP requests, provided configuration conditions beyond the attacker's direct control are also met. Successful exploitation produces a heap buffer overflow in the NGINX worker process that can cause a restart; under additional constraints such as disabled ASLR or successful ASLR bypass, the same flaw permits remote code execution.
Public advisories and technical disclosures at https://my.f5.com/manage/s/article/K000161019, https://depthfirst.com/nginx-rift, and https://github.com/DepthFirstDisclosures/Nginx-Rift address mitigation steps for supported versions.
The associated EPSS probability rose from a starting value of 0.0029 to a peak of 0.0104, indicating that exploitation interest increased after disclosure.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-30010
Vulnerability Data
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,…
more
$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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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V1.4.1
Mitigating Controls (NIST 800-53 r5) AI
Developer testing and evaluation (including fuzzing and memory-error detectors) can discover heap overflows after they have been coded.
Input validation enforces bounds checking on data written to heap buffers, directly stopping the overflow condition from being introduced.
Security engineering principles require use of memory-safe constructs and bounds-checked allocation routines that avoid introducing heap overflows.
Memory-protection mechanisms limit the ability of a heap overflow to execute attacker-controlled code or corrupt adjacent structures.
Flaw-remediation processes that include vulnerability scanning or static analysis will surface buffer-size errors.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly require bounds checking and safe memory handling that prevent heap overflows.
Vulnerability scanning and recording can discover heap-overflow flaws but does not prevent their introduction in code.
Timely patching removes known heap-overflow instances after they exist.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Secure coding standards directly require correct buffer-size calculations.
Security testing in development and acceptance can detect heap overflows before release.
Secure development lifecycle mandates practices that reduce the likelihood of introducing heap overflows.
Application security requirements can specify bounds-checking and safe memory APIs that mitigate heap overflows.
Secure architecture and engineering principles include memory-safety and input-validation controls that address heap overflows.
Change management ensures controlled deployment of fixes for discovered heap-overflow vulnerabilities.