ISC BIND up to 9.21.21 DNS-over-HTTPS use after free

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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7.5$0-$5k0.00

Summaryinfo

A vulnerability was found in ISC BIND up to 9.18.47/9.18.48-S0/9.20.22/9.20.22-S1/9.21.21. It has been classified as critical. This vulnerability affects unknown code of the component DNS-over-HTTPS. This manipulation causes use after free. This vulnerability appears as CVE-2026-3593. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability has been found in ISC BIND up to 9.18.47/9.18.48-S0/9.20.22/9.20.22-S1/9.21.21 and classified as critical. Affected by this vulnerability is an unknown code block of the component DNS-over-HTTPS. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

A use-after-free vulnerability exists within the DNS-over-HTTPS implementation. This issue affects BIND 9 versions 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, and 9.20.9-S1 through 9.20.22-S1. BIND 9 versions 9.18.0 through 9.18.48 and 9.18.11-S1 through 9.18.48-S1 are NOT affected.

The advisory is shared at kb.isc.org. This vulnerability is known as CVE-2026-3593 since 03/05/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Neither technical details nor an exploit are publicly available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 06/05/2026).

The vulnerability scanner Nessus provides a plugin with the ID 315660 (ISC BIND 9.20.0 < 9.20.23 / 9.20.9-S1 < 9.20.23-S1 / 9.21.0 < 9.21.22 Vulnerability (cve-2026-3593)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 9.18.48 or 9.18.48-S1 eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (315660) and CERT Bund (WID-SEC-2026-1626). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Debian Linux
  • Red Hat Enterprise Linux
  • Fedora Linux
  • Ubuntu Linux
  • Oracle Linux
  • Infoblox NIOS
  • SUSE openSUSE
  • Internet Systems Consortium BIND

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 7.6
VulDB Meta Temp Score: 7.5

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 9.8
NVD Vector: 🔒

CNA Base Score: 7.4
CNA Vector (isc): 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 315660
Nessus Name: ISC BIND 9.20.0 < 9.20.23 / 9.20.9-S1 < 9.20.23-S1 / 9.21.0 < 9.21.22 Vulnerability (cve-2026-3593)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: BIND 9.18.48/9.18.48-S1

Timelineinfo

03/05/2026 CVE reserved
05/20/2026 +75 days Advisory disclosed
05/20/2026 +0 days VulDB entry created
06/05/2026 +16 days VulDB entry last update

Sourcesinfo

Vendor: isc.org

Advisory: kb.isc.org
Status: Confirmed

CVE: CVE-2026-3593 (🔒)
GCVE (CVE): GCVE-0-2026-3593
GCVE (VulDB): GCVE-100-364873
CERT Bund: WID-SEC-2026-1626 - Internet Systems Consortium BIND: Mehrere Schwachstellen

Entryinfo

Created: 05/20/2026 15:38
Updated: 06/05/2026 14:31
Changes: 05/20/2026 15:38 (65), 05/20/2026 23:54 (2), 05/21/2026 17:27 (7), 05/23/2026 22:24 (11), 05/26/2026 15:40 (1), 06/05/2026 14:31 (1)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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