CVE-2026-42945
NGINX ngx_http_rewrite_module vulnerability
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
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 for the CVE license. View the record on cve.org
Key data
CVSS 4.0 Critical 9.2
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
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.
| 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
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
| 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
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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.
| 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. |
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EPSS
- 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
- Automatable
- no
- Technical impact
- total
Weakness (CWE)
Affected products
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
Timeline
- ID reserved
- Record published
- Record last updated
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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, 19:50 UTC. Sources and licenses