CVE-2026-27651
Denial of Service in NGINX ngx_mail_auth_http_module via Auth-Wait
Publication date: 2026-03-24
Last updated on: 2026-03-30
Assigner: F5 Networks
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r32 |
| f5 | nginx_plus | r35 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | From r33 (inc) to r35 (exc) |
| f5 | nginx_plus | r35 |
| f5 | nginx_plus | r36 |
| f5 | nginx_open_source | From 1.29.0 (inc) to 1.29.7 (exc) |
| f5 | nginx_plus | r32 |
| f5 | nginx_open_source | From 1.0.0 (inc) to 1.28.3 (exc) |
| f5 | nginx_open_source | From 0.5.15 (inc) to 0.9.7 (inc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-476 | The product dereferences a pointer that it expects to be valid but is NULL. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability occurs in the ngx_mail_auth_http_module module when it is enabled on NGINX Plus or NGINX Open Source. Specifically, if CRAM-MD5 or APOP authentication is enabled and the authentication server allows retries by returning the Auth-Wait response header, certain undisclosed requests can cause the worker processes to terminate unexpectedly.
How can this vulnerability impact me? :
The impact of this vulnerability is that it can cause worker processes in NGINX to terminate, leading to potential denial of service. This means that the affected server could become unavailable or unstable, disrupting services that rely on NGINX for mail authentication.