Vulnerability-Lookup

GHSA-5FV2-2P94-9GH7

Vulnerability from github – Published: 2026-03-25 15:31 – Updated: 2026-03-25 15:31

Details

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.

Severity ?

5.4 (Medium)


                  
                    CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

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{
  "affected": [],
  "aliases": [
    "CVE-2026-3591"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-305"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-03-25T14:16:37Z",
    "severity": "MODERATE"
  },
  "details": "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.\nThis 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.\nBIND 9 versions 9.18.0 through 9.18.46 and 9.18.11-S1 through 9.18.46-S1 are NOT affected.",
  "id": "GHSA-5fv2-2p94-9gh7",
  "modified": "2026-03-25T15:31:29Z",
  "published": "2026-03-25T15:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-3591"
    },
    {
      "type": "WEB",
      "url": "https://downloads.isc.org/isc/bind9/9.20.21"
    },
    {
      "type": "WEB",
      "url": "https://downloads.isc.org/isc/bind9/9.21.20"
    },
    {
      "type": "WEB",
      "url": "https://kb.isc.org/docs/cve-2026-3591"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-3591 (GCVE-0-2026-3591)

Vulnerability from cvelistv5 – Published: 2026-03-25 13:34 – Updated: 2026-03-25 14:13

Title

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

Summary

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.

Severity ?

5.4 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CWE

CWE-562 - Return of Stack Variable Address
CWE-305 - Authentication Bypass by Primary Weakness

Assigner

isc

References

URL

Tags

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

Impacted products

	Vendor	Product	Version
	ISC	BIND 9	Affected: 9.20.0 , ≤ 9.20.20 (custom) Affected: 9.21.0 , ≤ 9.21.19 (custom) Affected: 9.20.9-S1 , ≤ 9.20.20-S1 (custom) Unaffected: 9.18.0 , ≤ 9.18.46 (custom) Unaffected: 9.18.11-S1 , ≤ 9.18.46-S1 (custom)

Date Public ?

2026-03-25 00:00

Credits

ISC would like to thank Mcsky23 for bringing this vulnerability to our attention.

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JSON

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  "containers": {
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                  },
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                "role": "CISA Coordinator",
                "timestamp": "2026-03-25T14:12:43.295485Z",
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          ]
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        },
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        },
        {
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          "url": "https://downloads.isc.org/isc/bind9/9.21.20"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade to the patched release most closely related to your current version of BIND 9: 9.20.21, 9.21.20, or 9.20.21-S1."
        }
      ],
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}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-5FV2-2P94-9GH7

CVE-2026-3591 (GCVE-0-2026-3591)

Tags

Sightings

Nomenclature