CVE-2026-27651

Publication date 24 March 2026

Last updated 6 June 2026

Ubuntu priority

Cvss 3 Severity Score

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.

Status

Show unmaintained releases

Package	Ubuntu Release	Status
nginx	26.04 LTS resolute	Not affected
	25.10 questing	Fixed 1.28.0-6ubuntu1.2
	24.04 LTS noble	Fixed 1.24.0-2ubuntu7.7
	22.04 LTS jammy	Fixed 1.18.0-6ubuntu14.10
	20.04 LTS focal	Fixed 1.18.0-0ubuntu1.7+esm1
	18.04 LTS bionic	Fixed 1.14.0-0ubuntu1.11+esm2
	16.04 LTS xenial	Fixed 1.10.3-0ubuntu0.16.04.5+esm7
	14.04 LTS trusty	Fixed 1.4.6-1ubuntu3.9+esm6

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Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package	Patch details
nginx	Upstream: 0f71dd8

Severity score breakdown

Parameter	Value
Base score	7.5 · High
Attack vector	Network
Attack complexity	Low
Privileges required	None
User interaction	None
Scope	Unchanged
Confidentiality	None
Integrity impact	None
Availability impact	High
Vector	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

Related Ubuntu Security Notices (USN)

USN-8375-1
nginx vulnerabilities
3 June 2026