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CVE-2026-3591

A stack use-after-return flaw in SIG(0) handling code may enable ACL bypass

Published: Mar 25, 2026Updated: May 21, 2026 Sources: CVE List NVDCWE-305
NVD MITRE
5.4CVSSMEDIUM
EPSS Score
0.4%
Top 72.3%
CISA KEV
Not in KEV
Exploits
0 Known
Remediation
Patch Available

Description

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.

CVSS Vector Breakdown

AV:NAC:LPR:LUI:NS:UC:LI:LA:N
Exploitability
AV:NAttack Vector
Network
AC:LAttack Complexity
Low
PR:LPrivileges Required
Low
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:LConfidentiality
Low
I:LIntegrity
Low
A:NAvailability
None
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Weaknesses

CWE-305CWE-562

Affected Products

bindiscNetworking Infrastructure
BIND 9ISCNetworking Infrastructure
isccommercialUSNetworking Infrastructureaka internet systems consortium

Exploitability

0 exploit sources identified

Exploit details including PoC links, Metasploit modules, and scanner templates are available after registration.

View exploit details
Official Patch Available
Workaround Available

References

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

Timeline

Published
Mar 25, 2026
Last Updated
May 21, 2026

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