Assessment
Why it matters
EPSS is 0.7%; technical severity is CVSS 6.3.
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_http_charset_module module. When content is served or proxied through a location block with both source_charset utf-8; and a charset directive (for example, charset koi8-r;) configured, remote, unauthenticated attackers can send requests (in conjunction with conditions beyond their control) to cause a heap buffer over-read in the NGINX worker process, leading to limited disclosure of memory or a restart. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
Who should care
- Teams operating Dos, Nginx Gateway Fabric, Nginx Ingress Controller +4 more
- Vulnerability and exposure management teams
- Security operations teams monitoring exploitation activity
Response plan
What I would do
- Confirm whether Dos, Nginx Gateway Fabric, Nginx Ingress Controller +4 more is present in the environment.
- Identify affected versions and establish whether vulnerable services are exposed or reachable.
- F5 Security advisory K000161585
- Review relevant security telemetry for evidence of attempted or successful exploitation.
- Document the remediation decision and track it to verified completion.
Treatment intelligence
Remediation intelligence
Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.
Technical details
- CVSS vector
- CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:N/VA:L/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-125
- Affected versions
- F5 Dos (Start Including 4.3.0, End Including 4.7.0 | Version 4.9.0); F5 Nginx Gateway Fabric (Start Including 1.3.0, End Including 1.6.2 | Start Including 2.0.0, End Including 2.6.3); F5 Nginx Ingress Controller (Start Including 3.5.0, End Including 3.7.2 | Start Including 4.0.0, End Including 4.0.1 | Start Including 5.0.0, End Including 5.5.0); F5 Nginx Instance Manager (Start Including 2.17.0, End Including 2.22.0); F5 Nginx Open Source (Start Including 1.0.0, End Including 1.30.2 | Start Including 1.31.0, End Including 1.31.1); F5 Nginx Plus (Start Including 37.0.0.1, End Excluding 37.0.2.1 | Start Including r33, End Excluding r36 | Version r36 | Version r36); F5 Waf (Start Including 4.10.0, End Including 4.16.0 | Start Including 5.2.0, End Including 5.8.0 | Start Including 5.9.0, End Including 5.13.1)
- Fixed versions
- F5 Nginx Plus (Fixed from 37.0.2.1, r36)
- Published
- 17 June 2026
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
Signal timeline
- CVE published
- Latest EPSS score: 0.7%
- Signal calculated at 11