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Review reviewCritical

CVE-2026-3593

ISC BIND 9, Red Hat Hardened Images, Red Hat Enterprise Linux 10

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.

CVSS
9.8
EPSS
1.54%
72.4% percentile
CISA KEV
Not listed
Published
2026.05.20
PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability1.54%
Technical severityCVSS 9.8

Vulnerability overview

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.

Affected product and versions

Product
ISC BIND 9, Red Hat Hardened Images, Red Hat Enterprise Linux 10
Affected versions
>= 9.20.0 <= 9.20.22, >= 9.21.0 <= 9.21.21, >= 9.20.9-S1 <= 9.20.22-S1, >= 9.20.0 < 9.20.23, >= 9.21.0 < 9.21.22
Fixed versions
9.20.23, 9.21.22

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that ISC BIND 9, Red Hat Hardened Images, Red Hat Enterprise Linux 10 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE
CWE-416, CWE-825