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HIGH · 7.5

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 au...

Vulnerability Description

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.

CVSS Score

7.5

HIGH

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 Products

VendorProductVersions
F5Nginx Open Source>= 0.5.15, <= 0.9.7
F5Nginx Plus>= r33, < r35

Related Weaknesses (CWE)

CWE-476

References

FAQ

What is CVE-2026-27651?

CVE-2026-27651 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 au...

How severe is CVE-2026-27651?

CVE-2026-27651 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-27651?

Check the references section above for vendor advisories and patch information. Affected products include: F5 Nginx Open Source, F5 Nginx Plus.