CVE-2026-27651

| EUVD-2026-14880 HIGH
2026-03-24 f5
8.7
CVSS 4.0
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CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
X

Lifecycle Timeline

4
Patch Released
Apr 10, 2026 - 08:30 nvd
Patch available
Analysis Generated
Mar 24, 2026 - 14:45 vuln.today
EUVD ID Assigned
Mar 24, 2026 - 14:45 euvd
EUVD-2026-14880
CVE Published
Mar 24, 2026 - 14:13 nvd
HIGH 8.7

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.

Analysis

NGINX worker process crashes via null pointer dereference in the mail authentication module when CRAM-MD5 or APOP authentication is configured with retry-enabled backend servers. This denial of service vulnerability affects NGINX Plus and NGINX Open Source with no patch currently available, allowing unauthenticated remote attackers to terminate worker processes and degrade service availability.

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Remediation

Within 24 hours: Identify all NGINX instances with ngx_mail_auth_http_module enabled and document exposure scope. Within 7 days: Implement network segmentation to restrict access to mail proxy services and deploy WAF rules to filter malformed requests targeting authentication endpoints. …

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Priority Score

44
Low Medium High Critical
KEV: 0
EPSS: +0.0
CVSS: +44
POC: 0

Vendor Status

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CVE-2026-27651 vulnerability details – vuln.today

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