CVE-2026-5947

7.5 HIGH
Published: May 20, 2026 Modified: May 21, 2026
View on NVD

Description

Undefined behavior may result due to a race condition leading to a use-after-free violation. If BIND receives an incoming DNS message signed with SIG(0), it begins work to validate that signature. If, during that validation, the "recursive-clients" limit is reached (as would occur during a query flood), and that same DNS message is discarded per the limit, there is a brief window of time while the SIG(0) validation may attempt to read the now-discarded DNS message. 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 9.18.28 through 9.18.49 and 9.18.28-S1 through 9.18.49-S1 are NOT affected.

AI Explanation

Get an AI-powered plain-language explanation of this vulnerability and remediation steps.

Login to generate AI explanation

CVSS v3.x Details

0.0 Low Medium High Critical 10.0
Vector String
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://downloads.isc.org/isc/bind9/9.20.23
Source: security-officer@isc.org
Patch
https://downloads.isc.org/isc/bind9/9.21.22
Source: security-officer@isc.org
Patch
https://kb.isc.org/docs/cve-2026-5947
Source: security-officer@isc.org
Vendor Advisory

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
7.5 / 10.0
EPSS (Exploit Probability)
1.2%
65th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)

Affected Vendors

isc