ISC BIND up to 9.21.19 named return of stack variable address

Summaryinfo

A vulnerability classified as critical was found in ISC BIND up to 9.18.45/9.18.46-S0/9.20.20/9.20.20-S1/9.21.19. This vulnerability affects unknown code of the component named. The manipulation results in return of stack variable address. This vulnerability is identified as CVE-2026-3591. The attack can be executed remotely. There is not any exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, was found in ISC BIND up to 9.18.45/9.18.46-S0/9.20.20/9.20.20-S1/9.21.19. Affected is an unknown function of the component named. The manipulation with an unknown input leads to a return of stack variable address vulnerability. CWE is classifying the issue as CWE-562. A function returns the address of a stack variable, which will cause unintended program behavior, typically in the form of a crash. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at kb.isc.org. This vulnerability is traded as CVE-2026-3591 since 03/05/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are neither technical details nor an exploit publicly available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 03/31/2026).

The vulnerability scanner Nessus provides a plugin with the ID 303721 (Linux Distros Unpatched Vulnerability : CVE-2026-3591), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.20.21 or 9.21.20 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at Tenable (303721). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Domain Name Software

Vendor

• ISC

Name

• BIND

Version

• 9.18.0
• 9.18.1
• 9.18.2
• 9.18.3
• 9.18.4
• 9.18.5
• 9.18.6
• 9.18.7
• 9.18.8
• 9.18.9
• 9.18.10
• 9.18.11
• 9.18.12
• 9.18.13
• 9.18.14
• 9.18.15
• 9.18.16
• 9.18.17
• 9.18.18
• 9.18.19
• 9.18.20
• 9.18.21
• 9.18.22
• 9.18.23
• 9.18.24
• 9.18.25
• 9.18.26
• 9.18.27
• 9.18.28
• 9.18.29
• 9.18.30
• 9.18.31
• 9.18.32
• 9.18.33
• 9.18.34
• 9.18.35
• 9.18.36
• 9.18.37
• 9.18.38
• 9.18.39
• 9.18.40
• 9.18.41
• 9.18.42
• 9.18.43
• 9.18.44
• 9.18.45
• 9.18.46-S0
• 9.20.0
• 9.20.1
• 9.20.2
• 9.20.3
• 9.20.4
• 9.20.5
• 9.20.6
• 9.20.7
• 9.20.8
• 9.20.9
• 9.20.10
• 9.20.11
• 9.20.12
• 9.20.13
• 9.20.14
• 9.20.15
• 9.20.16
• 9.20.17
• 9.20.18
• 9.20.19
• 9.20.20
• 9.20.20-S1
• 9.21.0
• 9.21.1
• 9.21.2
• 9.21.3
• 9.21.4
• 9.21.5
• 9.21.6
• 9.21.7
• 9.21.8
• 9.21.9
• 9.21.10
• 9.21.11
• 9.21.12
• 9.21.13
• 9.21.14
• 9.21.15
• 9.21.16
• 9.21.17
• 9.21.18
• 9.21.19

License

• open-source

Website

• Vendor: https://www.isc.org/

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Entryinfo

VulDB is the best source for vulnerability data and more expert information about this specific topic.

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