What is CVE-2026-27651?

CVE-2026-27651 is a high-severity vulnerability in F5 Nginx Open Source, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-03-24.

How severe is CVE-2026-27651?

High severity. CVSS v3 base score is 7.5 out of 10.

NULL pointer dereference in F5 Nginx Open Source

CVE-2026-27651

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause worker processes to terminate. This issue may occur when (1) CRAM-MD5 or APOP authentication is enabled, and (2) the au…

EPSS: 0.001 (20.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

F5 Nginx Open Source — versions 1.29.0, 0.5.15
F5 Nginx Plus — versions R36, R35, R34

Weakness classification (CWE)

CWE-476 — NULL Pointer Dereference

References

my.f5.com/manage/s/article/K000160383 (vendor-advisory)

Frequently asked questions

What is CVE-2026-27651?: CVE-2026-27651 is a high-severity vulnerability in F5 Nginx Open Source, classified under NULL Pointer Dereference. CVSS score: 7.5/10. Published 2026-03-24.
How severe is CVE-2026-27651?: High severity. CVSS v3 base score is 7.5 out of 10.