Buffer overflow in F5 nginx Open Source

CVE-2026-27654

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.

Vulnerability class: Buffer Overflow

Published · last modified .

CVSS v3 metric

CVSS v3 base score 8.2 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H.

EPSS exploit prediction

EPSS: 0.251 (97.9th percentile), scored .

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 97.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-27654: held from 0.251 to 0.251.

EPSS over last 30 days · oldest: 0.251 · newest: 0.251 · change: 0.000

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2026-27654?
CVE-2026-27654 is a high-severity vulnerability in F5 nginx Open Source, classified under Heap-based Buffer Overflow. CVSS score: 8.2/10. Published 2026-03-24.
How severe is CVE-2026-27654?
High severity. CVSS v3 base score is 8.2 out of 10.
Is CVE-2026-27654 known to be exploited?
3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.