AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-367

https://access.redhat.com/errata/RHSA-2026:7412

https://access.redhat.com/security/cve/CVE-2026-5947

https://bugzilla.redhat.com/show_bug.cgi?id=2479772

https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-5947.json

[{"vendor":"Red Hat","product":"Red Hat Hardened Images","defaultStatus":"affected","cpes":["cpe:/a:redhat:hummingbird:1"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 10","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:10"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 6","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:6"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 7","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:7"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 8","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:8"]},{"vendor":"Red Hat","product":"Red Hat Enterprise Linux 9","defaultStatus":"unaffected","cpes":["cpe:/o:redhat:enterprise_linux:9"]},{"vendor":"Red Hat","product":"Red Hat OpenShift Container Platform 4","defaultStatus":"unaffected","cpes":["cpe:/a:redhat:openshift:4"]}]

{"timestamp":"2026-05-20T13:39:15.454199Z","id":"CVE-2026-5947","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}

[{"vendor":"ISC","product":"BIND 9","defaultStatus":"unaffected","versions":[{"version":"9.20.0","lessThanOrEqual":"9.20.22","versionType":"custom","status":"affected"},{"version":"9.21.0","lessThanOrEqual":"9.21.21","versionType":"custom","status":"affected"},{"version":"9.20.9-S1","lessThanOrEqual":"9.20.22-S1","versionType":"custom","status":"affected"},{"version":"9.18.28","lessThanOrEqual":"9.18.49","versionType":"custom","status":"unaffected"},{"version":"9.18.28-S1","lessThanOrEqual":"9.18.49-S1","versionType":"custom","status":"unaffected"}]}]

AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

OR
          *cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:* versions from (including) 9.20.0 up to (excluding) 9.20.23
          *cpe:2.3:a:isc:bind:*:*:*:*:-:*:*:* versions from (including) 9.21.0 up to (excluding) 9.21.22

Internet Systems Consortium (ISC): https://downloads.isc.org/isc/bind9/9.20.23 Types: Patch

Internet Systems Consortium (ISC): https://downloads.isc.org/isc/bind9/9.21.22 Types: Patch

Internet Systems Consortium (ISC): https://kb.isc.org/docs/cve-2026-5947 Types: Vendor Advisory

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.

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE-362

CWE-416

https://downloads.isc.org/isc/bind9/9.20.23

https://downloads.isc.org/isc/bind9/9.21.22

https://kb.isc.org/docs/cve-2026-5947