Advisory severityMedium4.4Red Hat Linux

Medium [CVE-2026-77955] ZONEMD verification bypass due to asynchronous DNSSEC resolution

This medium-severity Red Hat Linux advisory covers CVE-2026-77955; related products: Red Hat Hardened Images, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 8.

Aggregated and source-linked by VulniPulse. Data sources, validation and limitations.

CVE-2026-77955 Source published Sep 16, 2026Source updated Sep 16, 2026

VulniPulse record published Sep 16, 2026Record updated Sep 23, 2026

CVE-2026-77955

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Summary

ZONEMD verification bypass due to asynchronous DNSSEC resolution. Red Hat rates this moderate (CVSS 4.4).

Weakness: CWE-345. Red Hat lists fixing advisory RHSA-2026:68590 with package unbound-main-1.26.1-1.hum1.

Affected products named by the advisory: Red Hat Hardened Images; Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 8; Red Hat Enterprise Linux 9; and 2 more.

Affected products named by the advisory: Red Hat OpenShift Container Platform 4; Red Hat package: unbound.

Affected versions

< 1.13.2
< 1.26.1

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Fixed versions

unbound-main-1.26.1-1.hum1
RHSA-2026:68590

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

Mitigation checklist

Recommended fix / mitigation

To mitigate this issue, avoid configuring Unbound with `zonemd-check: yes` for zones located below a trust anchor, especially when the `zonefile` option is also enabled. If ZONEMD is required, ensure that zones are not configured in a way that allows for this asynchronous resolution vulnerability. Disabling the `zonemd-check` option or removing the `zonefile` option for affected zones can prevent the attack window. A restart of the Unbound service is required for configuration changes to take effect.

Official advisory · high-confidence parse· fetched 14 days ago·verify at source

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