CVE intelligence and bounded remediation

CVE-2026-28755 — F5 Nginx Plus security vulnerability

Medium CVSS 5.4

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.

Severity
Medium
CVSS
5.4 (3.1)
Published
2026-03-24
CISA KEV
Not currently listed
Ecosystem
software/application
Weaknesses
CWE-863

Affected products

  • f5 / nginx_plus / r33
  • f5 / nginx_plus / r34
  • f5 / nginx_plus / r35
  • f5 / nginx_plus / r36
  • f5 / nginx_open_source

Showing 5 representative product identities from 14 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.

Matched remediation archetype

Authorization bypass, IDOR, and cross-tenant access

This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.

Check exposure

  • Map object and action authorization checks across API, UI, batch, import/export, and background-job paths.
  • Identify tenant, ownership, role, and policy boundaries for affected resources and administrative operations.
  • Use synthetic fixtures to compare intended access matrices without accessing another user's real data.

Remediate safely

  • Enforce server-side authorization at each resource access and state transition using the authenticated principal and trusted tenant context.
  • Scope data queries by tenant and ownership; treat client-supplied identifiers, roles, and policy claims as untrusted.
  • Add deny-by-default policy tests for horizontal and vertical access across every affected transport.

Authoritative sources

Complete CVE record and remediation plan

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