CVE-2026-27651CWE-476

NGINX ngx_mail_auth_http_module vulnerability

High · published March 24, 2026

CVSS v4.0
8.7
EPSS
2%
Percentile
77.1
In the wild
Unconfirmed
What it is

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 authentication server permits retry by returning the Auth-Wait response header. Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.

The record
Technical detail
CVSS v4.0
8.7 · HIGH
Vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
EPSS
0.01707 · 77.1th percentile
Weakness
CWE-476 · NULL Pointer Dereference
Published
2026-03-24T14:13Z
EPSS history
Timeline
  • 24 MAR 14:13Z
    NGINX ngx_mail_auth_http_module vulnerability
    cvelistv5