CVE-2026-27654: f5 nginx open source Heap-based Buffer Overflow

Vulnerability summary

CVE-2026-27654 is a high (CVSS 8.8) Heap-based Buffer Overflow vulnerability in f5 nginx open source. EPSS estimates a 25.07% chance of exploitation in the next 30 days, higher than 97.9% of scored vulnerabilities.

Timeline

1. 24-03-2026
   PublishedVulnerability first disclosed.
2. 15-07-2026
   Last modifiedVulnerability information updated.

Description

NGINX Open Source and NGINX Plus have a vulnerability in the ngx_http_dav_module module that might allow an attacker to trigger a buffer overflow to the NGINX worker process; this vulnerability may result in termination of the NGINX worker process or modification of source or destination file names outside the document root. This issue affects NGINX Open Source and NGINX Plus when the configuration file uses DAV module MOVE or COPY methods, prefix location (nonregular expression location configuration), and alias directives. The integrity impact is constrained because the NGINX worker process user has low privileges and does not have access to the entire system. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

• CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
• CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.