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.

Attack Vector Network

Attack Complexity Low

Privileges Required None

Attack Requirements None

User Interaction None

Vulnerable System Confidentiality Impact None

Vulnerable System Integrity Impact None

Vulnerable System Availability Impact High

Subsequent System Confidentiality Impact None

Subsequent System Integrity Impact None

Subsequent System Availability Impact None

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

No EPSS score available.

Exploitation none

Automatable yes

Technical Impact partial

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
F5 NGINX Open Source unknown
Version Status Constraints
1.29.0 affected
< 1.29.7
0.5.15 affected
< 1.28.3
F5 NGINX Plus unaffected
Version Status Constraints
R36 affected
< R36 P3
R35 affected
< R35 P2
R34 affected
< *
R33 affected
< *
R32 affected
< R32 P5

No data.

No data.

No data.

Subscriptions

No data.

Tracking

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Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.

Workaround

No workaround given by the vendor.

References
Link Providers
https://my.f5.com/manage/s/article/K000160383 cve-icon cve-icon cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-27651 cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-27651 cve-icon
History

Wed, 25 Mar 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 threat_severity

Important

Tue, 24 Mar 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Tue, 24 Mar 2026 14:45:00 +0000

Type Values Removed Values Added
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.
Title NGINX ngx_mail_auth_http_module vulnerability
Weaknesses CWE-476
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}

cvssV4_0

{'score': 8.7, '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'}
cve-icon MITRE

Status: PUBLISHED

Assigner: f5

Published:

Updated: 2026-03-24T15:14:13.220Z

Reserved: 2026-03-18T16:06:38.454Z

Link: CVE-2026-27651

cve-icon Vulnrichment

Updated: 2026-03-24T15:14:09.900Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-24T15:16:32.910

Modified: 2026-03-24T15:53:48.067

Link: CVE-2026-27651

cve-icon Redhat

Severity : Important

Publid Date: 2026-03-24T14:13:27Z

Links: CVE-2026-27651 - Bugzilla

cve-icon OpenCVE Enrichment

No data.

Weaknesses