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CVE-2026-5947

7.5 · HIGH

Undefined behavior may result due to a race condition leading to a use-after-free violation.

Published May 20, 2026CWE-362EPSS 0.80%

Overview

CVE-2026-5947 is a high-severity vulnerability. It was published on May 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message.

This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1.

BIND 9 versions 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Refdownloads.isc.org/isc/bind9/9.20.23Refdownloads.isc.org/isc/bind9/9.21.22Refkb.isc.org/docs/cve-2026-5947Refaccess.redhat.com/errata/RHSA-2026:7412Refaccess.redhat.com/security/cve/CVE-2026-5947Refbugzilla.redhat.com/show_bug.cgi?id=2479772Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5947.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-5947?

CVE-2026-5947 is a high-severity vulnerability. It was published on May 20, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).

How severe is CVE-2026-5947?

This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-5947?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-5947?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-5947 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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