CVE-2026-3591: exploitation status and patch state

CVE-2026-3591 · CVSS 5.4 MEDIUM · EPSS <1% · patch available

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.

Is CVE-2026-3591 exploited?

• Not in the CISA KEV catalog.
• EPSS puts exploitation in the next 30 days at <1%.
• Public exploit code: none found in monitored sources.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

• CBL-Mariner Releases

What PlainSec published about CVE-2026-3591

• BIND 9 Updates Patch High-Severity Resolver DoS Flaws (2026-03-27)

Primary sources

• NVD record

What this record does not say

• No affected package data.

KEV and EPSS are re-checked daily. Record last updated 2026-08-11.