Medium · published June 17, 2026
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.
| Product | Versions | Fixed in |
|---|---|---|
| f5/dos | ≥ 4.3.0, ≤ 4.7.0 | — |
| f5/dos | all versions | — |
| f5/nginx_gateway_fabric | ≥ 1.3.0, ≤ 1.6.2 | — |
| f5/nginx_gateway_fabric | ≥ 2.0.0, ≤ 2.6.3 | — |
| f5/nginx_ingress_controller | ≥ 3.5.0, ≤ 3.7.2 | — |
| f5/nginx_ingress_controller | ≥ 4.0.0, ≤ 4.0.1 | — |
| f5/nginx_ingress_controller | ≥ 5.0.0, ≤ 5.5.0 | — |
| f5/nginx_instance_manager | ≥ 2.17.0, ≤ 2.22.0 | — |
| f5/nginx_open_source | ≥ 1.0.0, ≤ 1.30.2 | — |
| f5/nginx_open_source | ≥ 1.31.0, ≤ 1.31.1 | — |
| f5/nginx_plus | ≥ 37.0.0.1, < 37.0.2.1 | 37.0.2.1 |
| f5/nginx_plus | ≥ r33, < r36 | r36 |
| f5/nginx_plus | all versions | — |
| f5/nginx_plus | all versions | — |
| f5/nginx_plus | all versions | — |
| f5/nginx_plus | all versions | — |
| f5/nginx_plus | all versions | — |
| f5/nginx_plus | all versions | — |
| f5/waf | ≥ 4.10.0, ≤ 4.16.0 | — |
| f5/waf | ≥ 5.2.0, ≤ 5.8.0 | — |
| f5/waf | ≥ 5.9.0, ≤ 5.13.1 | — |