What is CVE-2026-94300?

CVE-2026-94300 is a high-severity vulnerability in Isc Bind 9, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 8.1/10. Published 2026-10-21.

How severe is CVE-2026-94300?

High severity. CVSS v3 base score is 8.1 out of 10.

Double Free in Isc Bind 9

CVE-2026-94300

Replaying GSS-TSIG signed UDP messages can result in memory corruption in "`named`". An attacker who can capture a previously signed UDP message can replay it while the negotiated TSIG key is still valid. By also sending crafted queries to a zone the attacker controls, the attacker may potentially achieve remote code execution. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.29, 9.21.0 through 9.21.26, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.29-S1.

Vulnerability class: Race Condition

Published 2026-10-21 · last modified 2026-10-21.

CVSS v3 metric

CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.

Affected products

Isc Bind 9

Weakness classification (CWE)

References

kb.isc.org/docs/cve-2026-94300 (vendor-advisory)
downloads.isc.org/isc/bind9/9.20.30 (patch)
downloads.isc.org/isc/bind9/9.21.27 (patch)

Frequently asked questions

What is CVE-2026-94300?: CVE-2026-94300 is a high-severity vulnerability in Isc Bind 9, classified under Concurrent Execution using Shared Resource with Improper Synchronization (Race Condition). CVSS score: 8.1/10. Published 2026-10-21.
How severe is CVE-2026-94300?: High severity. CVSS v3 base score is 8.1 out of 10.