CVE-2026-28755
Improper Revoked Certificate Validation in NGINX TLS Module
Publication date: 2026-03-24
Last updated on: 2026-03-26
Assigner: F5 Networks
Description
Description
CVSS Scores
EPSS Scores
| Probability: | |
| Percentile: |
Meta Information
Affected Vendors & Products
| Vendor | Product | Version / Range |
|---|---|---|
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r33 |
| f5 | nginx_plus | r34 |
| f5 | nginx_plus | r35 |
| f5 | nginx_plus | r36 |
| f5 | nginx_plus | r36 |
| f5 | nginx_open_source | From 0.5.13 (inc) to 0.9.7 (inc) |
| f5 | nginx_open_source | From 1.27.2 (inc) to 1.28.3 (exc) |
| f5 | nginx_open_source | From 1.29.0 (inc) to 1.29.7 (exc) |
Helpful Resources
Exploitability
| CWE ID | Description |
|---|---|
| CWE-863 | The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check. |
Attack-Flow Graph
AI Powered Q&A
Can you explain this vulnerability to me?
This vulnerability exists in the ngx_stream_ssl_module of NGINX Plus and NGINX Open Source. It occurs because the software improperly handles revoked certificates when configured with the ssl_verify_client on and ssl_ocsp on directives. As a result, the TLS handshake can still succeed even if an OCSP check has identified the certificate as revoked.
How can this vulnerability impact me? :
Because the TLS handshake can succeed despite a certificate being revoked, an attacker could potentially use a revoked certificate to establish a secure connection. This undermines the trust model of TLS, potentially allowing unauthorized access or interception of communications that are expected to be secure.
How does this vulnerability affect compliance with common standards and regulations (like GDPR, HIPAA)?:
I don't know
How can this vulnerability be detected on my network or system? Can you suggest some commands?
I don't know
What immediate steps should I take to mitigate this vulnerability?
I don't know