CVE-2026-28755

MEDIUMCVSS 5.4/10EPSS 0.13%

Last modified

CVE-2026-28755 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. 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.. EPSS estimates a 0.13% chance of exploitation in the next 30 days.

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.

Metrics

Weakness Enumeration

Affected Software

VendorProductVersionsUpdate
F5Nginx Plusr33—
F5Nginx Plusr34—
F5Nginx Plusr35P1
F5Nginx Plusr36—
F5Nginx Open Source>= 0.5.13, <= 0.9.7—
F5Nginx Open Source>= 1.27.2, < 1.28.3—
F5Nginx Open Source>= 1.29.0, < 1.29.7—

References

Timeline

Published
Last Modified
Status
Analyzed

Frequently Asked Questions

What is CVE-2026-28755?
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.
How severe is CVE-2026-28755?
CVE-2026-28755 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 0.13% probability of exploitation in the next 30 days.
How do I fix CVE-2026-28755?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST