CVE-2026-28755
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Improper Revoked Certificate Validation in NGINX TLS Module

Publication date: 2026-03-24

Last updated on: 2026-03-26

Assigner: F5 Networks

Description
NGINX Plus and NGINX Open Source have a vulnerability in the ngx_stream_ssl_module module due to the improper handling of revoked certificates when configured with the ssl_verify_client on and ssl_ocsp on directives, allowing the TLS handshake to succeed even after an OCSP check identifies the certificate as revoked.   Note: Software versions which have reached End of Technical Support (EoTS) are not evaluated.
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Meta Information
Published
2026-03-24
Last Modified
2026-03-26
Generated
2026-06-16
AI Q&A
2026-03-24
EPSS Evaluated
2026-06-15
NVD
CVE-2026-28755
EUVD
EUVD-2026-14887
Affected Vendors & Products
Showing 14 associated CPEs
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)
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Exploitability
CWE
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KEV
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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.
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Executive Summary

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.

Impact Analysis

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.

Compliance Impact

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Detection Guidance

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