CVE-2026-3591

5.4 mediumEPSS 0.4%

A use-after-return vulnerability exists in the `named` server when handling DNS queries signed with SIG(0). Using a specially-crafted DNS request, an attacker may be able to cause an ACL to improperly (mis)match an IP address. In a default-allow ACL (denying only specific IP addresses), this may lead to unauthorized access. Default-deny ACLs should fail-secure. This issue affects BIND 9 versions 9.20.0 through 9.20.20, 9.21.0 through 9.21.19, and 9.20.9-S1 through 9.20.20-S1. BIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.

Severity

CVSS 3.1

5.4 medium

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

EPSS: 0.4% chance of exploitation in the next 30 days; higher than 30% of CVEs (scores of 2026-10-31)
CWEs: CWE-305, CWE-562
Published: 2026-03-25
Modified: 2026-06-17
Record from: the NVD, synced 2026-10-19

Affected

isc:bind

References

https://downloads.isc.org/isc/bind9/9.20.21
https://downloads.isc.org/isc/bind9/9.21.20
https://kb.isc.org/docs/cve-2026-3591

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