CVE-2026-27651
NGINX ngx_mail_auth_http_module vulnerability
CVSS Score
7.5
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-476 |
| Vendor | f5 |
| Product | nginx open source |
| Published | Mar 24, 2026 |
| Last Updated | Jul 15, 2026 |
Stay Ahead of the Next One
Get instant alerts for f5 nginx open source
Be the first to know when new high vulnerabilities affecting f5 nginx open source are published — delivered to Slack, Telegram or Discord.
Get Free Alerts →
Free · No credit card · 60 sec setup
CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High
Affected Versions
F5 / NGINX Open Source
1.29.0 < 1.29.7 0.5.15 < 1.28.3
F5 / NGINX Plus
R36 < R36 P3 R35 < R35 P2 R34 < * R33 < * R32 < R32 P5
References
my.f5.com: https://my.f5.com/manage/s/article/K000160383 access.redhat.com: https://access.redhat.com/security/cve/CVE-2026-27651 bugzilla.redhat.com: https://bugzilla.redhat.com/show_bug.cgi?id=2450791 security.access.redhat.com: https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27651.json access.redhat.com: https://access.redhat.com/errata/RHSA-2026:13634 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:6906 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:6907 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:15942 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:14836 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:13839 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:15943 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:15945 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:13680 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:15966 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:6923 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:7002 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:7343 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:8346 access.redhat.com: https://access.redhat.com/errata/RHSA-2026:10065
Credits
🔍 F5 acknowledges Arkadi Vainbrand for bringing this issue to our attention and following the highest standards of coordinated disclosure.