Medium5.9Red Hat Linux

Medium [CVE-2026-40355] Denial of Service via NULL pointer dereference in NegoEx mechanism

This medium-severity Red Hat Linux advisory covers CVE-2026-40355 affecting Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 1.

CVE-2026-40355 Published Apr 28, 2026

CVE-2026-40355

Affected products & platforms

Red Hat LinuxUnclassified

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Summary

Denial of Service via NULL pointer dereference in NegoEx mechanism. Red Hat rates this moderate (CVSS 5.9).

Weakness: CWE-476. Affected package(s): krb5-main, insights-proxy/insights-proxy-container-rhel9:1780420428, rhui5/haproxy-rhel9:1779798164, krb5, discovery/discovery-ui-rhel9:1782166952, discovery/discovery-server-rhel9:1782159791.

Resolved in Red Hat advisory RHSA-2026:12220 — update the affected packages (`sudo dnf update`).

Affected products named by the advisory: Red Hat Enterprise Linux 9; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 1.

Affected versions

krb5-main-1.22.2-7.hum1
insights-proxy/insights-proxy-container-rhel9:1780420428
rhui5/haproxy-rhel9:1779798164
krb5-0:1.21.1-10.el9_8
krb5-0:1.18.2-34.el8_10
discovery/discovery-ui-rhel9:1782166952
discovery/discovery-server-rhel9:1782159791
rhui5/rhua-rhel9:1779798222
krb5-0:1.21.3-10.el10_2
rhui5/cds-rhel9:1779798159
rhui5/installer-rhel9:1779798165

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Fixed versions

RHSA-2026:12220

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

Mitigation checklist

Recommended fix / mitigation

Update the affected package(s) to the fixed version shipped in RHSA-2026:12220 (`sudo dnf update` / `yum update`).

Official advisory · high-confidence parse· fetched 2 months ago·verify at source

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