SECUFOCUSNOW
Home›CVE index›CVE-2026-42945
Priority reviewCritical

CVE-2026-42945

F5 NGINX Plus, NGINX Open Source, Red Hat Enterprise Linux 10

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 execut...

CVSS
9.2
EPSS
61.5%
99.1% percentile
CISA KEV
Not listed
Published
2026.05.14
PRIORITY ASSESSMENT

Priority review

FIRST EPSS indicates an elevated probability of exploitation.

Known exploitationNot established by KEV
Exploit probability61.5%
Technical severityCVSS 9.2

Vulnerability overview

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 execut...

Affected product and versions

Product
F5 NGINX Plus, NGINX Open Source, Red Hat Enterprise Linux 10
Affected versions
>= R36 < R36 P4, >= R32 < R32 P6, >= 0.6.27 < 1.30.1, >= 4.3.0 <= 4.7.0, 4.8.0, >= 1.3.0 <= 1.6.2, >= 2.0.0 <= 2.5.1, >= 3.5.0 <= 3.7.2, >= 4.0.0 <= 4.0.1, >= 5.0.0 <= 5.4.1, >= 2.16.0 <= 2.21.1, >= 0.6.27 <= 1.30.0, >= r32 <= r36, >= 4.9.0 <= 4.16.0, >= 5.1.0 <= 5.8.0, >= 5.9.0 <= 5.12.1
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that F5 NGINX Plus, NGINX Open Source, Red Hat Enterprise Linux 10 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS 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:X
CWE
CWE-122, CWE-131
CVE-2026-42945 — F5 NGINX Plus, NGINX Open Source, Red Hat Enterprise Linux 10 | SECUFOCUS NOW