Home/CVE/When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause
CVE

CVE-2026-27651

When the ngx_mail_auth_http_module module is enabled on NGINX Plus or NGINX Open Source, undisclosed requests can cause

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.

HIGH · CVSS 7.5 EPSS 0.00064
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-476NULL Pointer Dereference
▤

Affected Products & Versions

5
f5 nginx open source>= 0.5.15 and <= 0.9.7
f5 nginx open source>= 1.0.0 and < 1.28.3
f5 nginx open source>= 1.29.0 and < 1.29.7
f5 nginx plus>= r33 and < r35
f5 nginx plusall versions
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · f5sirt@f5.com
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Mar 2026 · 03:16 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
⚑

Vendor Advisories

18
usnUSN-8375-1
rhsaRHSA-2026:10065Moderate
msrcCVE-2026-27651
suse-csafopenSUSE-SU-2026:10423-1
rhsaRHSA-2026:6906Important
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://my.f5.com/manage/s/article/K000160383Vendor Advisory
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