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Vulnerabilities

Vulnerability · CVE-2026-3591

A use-after-return vulnerability exists in the server when handling DNS queries signed with SIG(0).

Published Mar 25, 2026 · catalog updated Jun 17, 2026 · A use-after-return vulnerability exists

Check if you run it

No confirmed exploitation is on record for CVE-2026-3591. EPSS is 0.32%. Act only if a listed version of A use-after-return vulnerability exists is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A use-after-return vulnerability exists).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium5.4
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.32%
Remediation
Advisory link
Affected products
cpe isc/bind

A use-after-return vulnerability exists in the 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe isc/bindversion unspecified

How to fix CVE-2026-3591

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3591. EPSS is 0.32%. Act only if a listed version of A use-after-return vulnerability exists is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-305; CWE-562. EPSS 0.32%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 25, 2026 · NIST NVD

    Detected

    A use-after-return vulnerability exists in the 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 th

  2. Jun 17, 2026 · NIST NVD

    Updated

    A use-after-return vulnerability exists in the 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 th

Sources

  • CVE.orgVulnerability recordCVE-2026-3591

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3591

    30-day exploitation probability 0.3%

    first.org
  • NIST NVDVulnerability recordCVE-2026-3591

    A use-after-return vulnerability exists in the 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 addr

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.