CVE-2026-3591
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.
- Score
- CVSS 3.1 5.4 Medium
- Status
- Analyzed - security-officer@isc.org
- Published
- 2026-03-25
- Last modified
- 2026-03-25
- Weaknesses
- CWE-305, CWE-562
Affected products
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
