CVE-2026-27651
7.5 · HIGHOverview
CVE-2026-27651 is a high-severity vulnerability affecting f5 nginx_open_source. It was published on March 24, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical 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.
Remediation
Check the references section for vendor advisories and patches from f5. Update nginx_open_source to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected Products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| f5 | nginx_open_source | 0.5.15 | Affected |
| f5 | nginx_plus | >= r33, < r35 | Affected |
References
Frequently Asked Questions
What is CVE-2026-27651?
CVE-2026-27651 is a high-severity vulnerability affecting f5 nginx_open_source. It was published on March 24, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-27651?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-27651?
Check the references section for vendor advisories and patches from f5. Update nginx_open_source to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-27651?
CyberStrike's AI-powered security agents can automatically detect CVE-2026-27651 across your infrastructure using autonomous pentesting, DAST scanning, and HackBrowser. The platform continuously monitors for known vulnerabilities and provides actionable remediation guidance prioritized by real-world exploitability.
How CyberStrike Helps
AI agents map your attack surface to find vulnerabilities like this one.
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