VulnTideExploited vulnerabilities, by vendor. Data as of .
Not in CISA KEVPublished EPSS 68% probability of exploitation in 30 days
F5

CVE-2026-42945: NGINX ngx_http_rewrite_module vulnerability

Is it exploited?

Not on CISA's list. CISA has not added it to the Known Exploited Vulnerabilities catalog as of . If CISA adds it, this page shows it as known exploited.

How likely is exploitation in the next 30 days?
68%

EPSS score, percentile 99.3 of all scored records. A probability estimated by FIRST, not a report of exploitation.

How severe?
9.2 Critical

CVSS v4.0 base score, given by the CNA

What should I do?

CISA has set no required action, because the vulnerability is not in KEV.

Advisories and patches (1)

Which versions are affected?

Affected

  • from R36 to before R36 P4
  • from R32 to before R32 P6
  • from 0.6.27 to before 1.30.1

Unaffected R37; 1.31.0

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

What to do

Advisories and patches

Affected products and versions

As listed in the CVE record.

F5 NGINX Plus
StatusVersions
UnaffectedR37
Affectedfrom R36 to before R36 P4
Affectedfrom R32 to before R32 P6

Versions not listed are: unknown.

F5 NGINX Open Source
StatusVersions
Unaffected1.31.0
Affectedfrom 0.6.27 to before 1.30.1

Versions not listed are: unaffected.

Versions the record lists as unaffected: R37, 1.31.0.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

About this vulnerability

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 i…

Summary: CVE record, as of .

  • CISA has not added CVE-2026-42945 to its Known Exploited Vulnerabilities (KEV) catalog, as of 28 Oct 2026.
  • The CVE record was published on 13 May 2026.
  • The CVE record carries a CVSS v4.0 base score of 9.2 (Critical), given by its CNA.
  • FIRST's EPSS model puts the probability of exploitation in the next 30 days at 68% (percentile 99.3), as of 28 Oct 2026. EPSS is a statistical estimate, not a report of exploitation.
  • CISA's SSVC assessment in the CVE record: exploitation none, automatable no, technical impact total.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of ; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of ; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of . About the data.

Description

NGINX ngx_http_rewrite_module vulnerability

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.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of . About the data.

Weakness

  • CWE-122: Heap-based Buffer Overflow.

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record.

Timeline

DateEvent
CVE record published
CVE record last updated

Known exploited F5 vulnerabilities

  • CVE-2026-94127: F5 BIG-IP APM Heap-based Buffer Overflow Vulnerability (added )
  • CVE-2025-53521: F5 BIG-IP Stack-Based Buffer Overflow Vulnerability (added )
  • CVE-2023-46747: F5 BIG-IP Configuration Utility Authentication Bypass Vulnerability (added )
  • CVE-2023-46748: F5 BIG-IP Configuration Utility SQL Injection Vulnerability (added )
  • CVE-2022-1388: F5 BIG-IP Missing Authentication Vulnerability (added )