Executive brief
NGINX is a widely-used web server that handles incoming HTTP requests. When NGINX is configured to use HTTP/3 (a newer internet protocol) with certain versions of OpenSSL, a memory corruption bug can occur during the TLS security handshake. An attacker can trigger this remotely to crash the web server, causing service outages, or potentially corrupt data in memory.
Technical details
This vulnerability is a heap buffer overflow in the ngx_http_v3_module module that occurs during TLS handshake processing in HTTP/3 connections when OpenSSL versions <= 3.5.0 are used under specific configurations. The overflow is non-deterministic and beyond an attacker's direct control. A remote attacker can exploit this without authentication by sending a specially crafted TLS handshake packet, leading to a worker process restart and/or limited data corruption. The vulnerability is data-plane only with no control-plane exposure. Patches should be available from NGINX; affected versions should be reviewed against official security advisories.
Affected products
- NGINX NGINX Plus versions using ngx_http_v3_module with OpenSSL <= 3.5.0
- NGINX NGINX Open Source versions using ngx_http_v3_module with OpenSSL <= 3.5.0
- OpenSSL OpenSSL <= 3.5.0
Timeline
- 2026-09-15: disclosed: Vulnerability published