CVE-2026-27651
What it is
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.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Exploit odds
- 1.0% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 1.0% in the next 30 days (EPSS).
- Severity: 8.7 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 1.0% · EPSS, next 30 days
- Weakness
- CWE-476 · NULL pointer dereference
- Record status
- Modified
Affected
- f5 nginx Open Source ≤ 0.9.7
- f5 nginx Open Source < 1.28.3
- f5 nginx Open Source < 1.29.7
- f5 nginx Plus < r35
- f5 nginx Plus r32
- f5 nginx Plus r35
- f5 nginx Plus r36
Attack profile CVSS 4.0 · 8.7
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- None
- Privileges needed
- None
- User interaction
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw 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
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-27651.md and follow it. Check whether this project is affected by CVE-2026-27651. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
References
- https://my.f5.com/manage/s/article/K000160383
- https://access.redhat.com/errata/RHSA-2026:10065
- https://access.redhat.com/errata/RHSA-2026:13634
- https://access.redhat.com/errata/RHSA-2026:13680
- https://access.redhat.com/errata/RHSA-2026:13839
- https://access.redhat.com/errata/RHSA-2026:14836
- https://access.redhat.com/errata/RHSA-2026:15942
- https://access.redhat.com/errata/RHSA-2026:15943
- https://access.redhat.com/errata/RHSA-2026:15945
- https://access.redhat.com/errata/RHSA-2026:15966
- https://access.redhat.com/errata/RHSA-2026:6906
- https://access.redhat.com/errata/RHSA-2026:6907
- https://access.redhat.com/errata/RHSA-2026:6923
- https://access.redhat.com/errata/RHSA-2026:7002
- https://access.redhat.com/errata/RHSA-2026:7343
- https://access.redhat.com/errata/RHSA-2026:8346
- https://access.redhat.com/security/cve/CVE-2026-27651
- https://bugzilla.redhat.com/show_bug.cgi?id=2450791
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-27651.json