--- title: "CVE-2026-42945: NGINX ngx_http_rewrite_module vulnerability | CubePath" description: "NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_rewrite_module module. This vulnerability exists when the rewrite directive…" language: en source: https://cubepath.com/security/cve/CVE-2026-42945 --- # CVE-2026-42945: NGINX ngx_http_rewrite_module vulnerability | CubePath ## 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. Official description from the CVE record, published by f5. Copyright © 1999-2026 The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CVE license. [View the record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-42945) ## Key data ### CVSS 4.0 Critical 9.2 Score published by f5 in the CVE record. 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 | Metric | Value | What it means | | ----------------------------------- | ------- | -------------------------------------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | High | The attacker has to evade or get around security controls that are in place, which takes target-specific work. | | Attack requirements | None | The attack works without any special deployment or execution conditions. | | Privileges required | None | No account or privileges are needed. | | User interaction | None | No action from any user is needed. | | Vulnerable system: confidentiality | High | Serious or total effect on the secrecy of data. | | Vulnerable system: integrity | High | Serious or total effect on the trustworthiness of data. | | Vulnerable system: availability | High | Serious or total effect on availability. | | Subsequent systems: confidentiality | None | No effect on other systems' data secrecy. | | Subsequent systems: integrity | None | No effect on other systems' data trustworthiness. | | Subsequent systems: availability | None | No effect on other systems' availability. | ### CVSS 3.1 High 8.1 Score published by f5 in the CVE record. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | Metric | Value | What it means | | ---------------------- | --------- | ----------------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | High | The attack depends on conditions outside the attacker's control, so it takes preparation. | | Privileges required | None | No account or privileges are needed. | | User interaction | None | No action from any user is needed. | | Scope | Unchanged | The impact stays within the vulnerable component. | | Confidentiality impact | High | Serious or total effect on the secrecy of data. | | Integrity impact | High | Serious or total effect on the trustworthiness of data. | | Availability impact | High | Serious or total effect on availability. | ### CVSS 3.1 High 8.1 Score published by redhat-SADP in the CVE record. CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H | Metric | Value | What it means | | ---------------------- | --------- | ----------------------------------------------------------------------------------------- | | Attack vector | Network | The vulnerable component can be reached over a network, possibly from the Internet. | | Attack complexity | High | The attack depends on conditions outside the attacker's control, so it takes preparation. | | Privileges required | None | No account or privileges are needed. | | User interaction | None | No action from any user is needed. | | Scope | Unchanged | The impact stays within the vulnerable component. | | Confidentiality impact | High | Serious or total effect on the secrecy of data. | | Integrity impact | High | Serious or total effect on the trustworthiness of data. | | Availability impact | High | Serious or total effect on availability. | CVSS is owned and managed by FIRST.Org, Inc. (FIRST) and is used by permission. Each CVSS score on this site is shown together with its vector string, as published in the CVE record by the source named next to it. Learn more at [first.org/cvss](https://www.first.org/cvss/) . ### EPSS Exploit Prediction Scoring System by FIRST: an estimate of the probability that exploitation activity will be observed in the next 30 days. Score 0.68047 (68.0% probability) Percentile 99.3% Scores of Nov 10, 2026 Model v2026.06.15 ### CISA assessment as of May 13, 2026 Stakeholder-Specific Vulnerability Categorization (SSVC) decision points added by CISA. Automatable no Technical impact total ### Weakness (CWE) CWE catalog version 5.0. CWE names: Copyright © 2006-2026, The MITRE Corporation. See [/security/cve/legal](https://cubepath.com/security/cve/legal) for the CWE license. - [CWE-122](https://cwe.mitre.org/data/definitions/122.html) Heap-based Buffer Overflow - [CWE-131](https://cwe.mitre.org/data/definitions/131.html) Incorrect Calculation of Buffer Size ## Affected products Products listed in the CVE record, as the CNA published them. - F5 NGINX Plus - unaffected: R37 up to before \* - affected: R36 up to before R36 P4 - affected: R32 up to before R32 P6 - F5 NGINX Open Source - unaffected: 1.31.0 up to before \* - affected: 0.6.27 up to before 1.30.1 ## References Links listed in the CVE record. They lead to other sites, which CubePath does not control. - [my.f5.com/manage/s/article/K000161019](https://my.f5.com/manage/s/article/K000161019) vendor-advisory patch - [depthfirst.com/nginx-rift](https://depthfirst.com/nginx-rift) - [github.com/DepthFirstDisclosures/Nginx-Rift](https://github.com/DepthFirstDisclosures/Nginx-Rift) ## Timeline 1. ID reserved Apr 30, 2026 2. Record published May 13, 2026 3. Record last updated Sep 10, 2026 ## Look up another CVE ## About CubePath CubePath is a cloud provider with data centers in Europe and the United States. It offers VPS, bare metal servers and DDoS protection. [Cloud VPS](https://cubepath.com/vps) [DDoS protection](https://cubepath.com/ddos-protection) Data from the CVE Program (MITRE), CISA KEV and FIRST EPSS. CVSS is owned by FIRST and used by permission. Not affiliated with or endorsed by MITRE, CISA or FIRST. Data as of Nov 10, 2026, 20:02 UTC. [Sources and licenses](https://cubepath.com/security/cve/legal)