A use-after-free vulnerability exists within the DNS-over-HTTPS implementation
Description
A use-after-free vulnerability exists within the DNS-over-HTTPS implementation
AI Analyst Comment
Remediation
Apply vendor security updates immediately. Monitor for exploitation attempts and review access logs.
---METADATA---
VENDOR: ISC
PRODUCT: BIND 9
AFFECTED_VERSIONS: 9.20.0-9.20.22, 9.21.0-9.21.21, 9.20.9-S1-9.20.22-S1
CONFIDENCE: high
MISSING: none
---END_METADATA---
Description Summary:
A use-after-free vulnerability in the DNS-over-HTTPS implementation of ISC BIND 9 may allow for memory corruption or unstable behavior.
Executive Summary:
A use-after-free vulnerability in the DNS-over-HTTPS implementation of ISC BIND 9 poses a risk of service disruption and potential memory exploitation.
Vulnerability Details
CVE-ID: CVE-2026-3593
Affected Software: ISC BIND 9
Affected Versions: 9.20.0 through 9.20.22, 9.21.0 through 9.21.21, 9.20.9-S1 through 9.20.22-S1
Vulnerability: This is a use-after-free vulnerability (CWE-416) within the DNS-over-HTTPS component. The vulnerability is triggered when the application improperly handles memory, which can lead to crashes or arbitrary code execution by an unauthenticated attacker.
Business Impact
The vulnerability carries a CVSS score of 7.4, indicating a High severity risk. Successful exploitation could lead to a denial-of-service (DoS) condition, impacting critical DNS infrastructure, or potentially allow an attacker to gain unauthorized control over the affected BIND server, compromising the integrity of network traffic.
Remediation Plan
Immediate Action: Upgrade immediately to the patched releases: 9.20.23, 9.21.22, or 9.20.23-S1.
Proactive Monitoring: Monitor BIND 9 process logs for unexpected termination or segmentation faults that may indicate an exploitation attempt.
Compensating Controls: If immediate patching is not feasible, consider disabling DNS-over-HTTPS functionality if it is not business-critical to mitigate the primary attack vector.
Exploitation Status
Public Exploit Available: false
Analyst Notes: As of May 22, 2026, there is no public information indicating active exploitation of this vulnerability. However, due to the nature of the flaw, the potential for exploitation is high.
Analyst Recommendation
Given the central role of DNS services, this vulnerability requires urgent attention. Administrators should prioritize patching BIND instances to the specified versions to prevent potential service instability and unauthorized access, ensuring that critical infrastructure remains resilient against exploitation.