PatchSiren cyber security CVE debrief
CVE-2026-66374 nic CVE debrief
CVE-2026-66374 is a high-severity vulnerability in Knot Resolver before 6.4.1, allowing remote code execution via a heap-based buffer overflow in the DoQ (DNS-over-QUIC) receive path. This vulnerability has a CVSS score of 8.1, indicating a high level of severity. The vulnerability exists due to a lack of proper input validation in the DoQ receive path, which allows an attacker to execute remote code. Users of Knot Resolver versions before 6.4.1 should be concerned about this vulnerability, as it could potentially lead to unauthorized access, data breaches, or other malicious activities.
- Vendor
- nic
- Product
- Knot Resolver
- CVSS
- HIGH 8.1
- CISA KEV
- Not listed in stored evidence
- Original CVE published
- 2026-07-25
- Original CVE updated
- 2026-07-27
- Advisory published
- 2026-07-25
- Advisory updated
- 2026-07-27
Who should care
Users of Knot Resolver versions before 6.4.1 should be concerned about this vulnerability, as it allows remote code execution. This could potentially lead to unauthorized access, data breaches, or other malicious activities. Operators, platform administrators, and security teams should review the vulnerability details and take necessary actions to mitigate the vulnerability.
Technical summary
The vulnerability exists in the DoQ (DNS-over-QUIC) receive path of Knot Resolver before 6.4.1. A heap-based buffer overflow occurs when processing certain inputs, allowing an attacker to execute remote code. The CVSS vector for this vulnerability is CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:L. The vulnerability is caused by a lack of proper input validation in the DoQ receive path, which allows an attacker to execute remote code. To mitigate this vulnerability, users should update Knot Resolver to version 6.4.1 or later.
Defensive priority
High priority should be given to updating Knot Resolver to version 6.4.1 or later to mitigate this vulnerability. Additionally, users should monitor their systems for any suspicious activity and implement compensating controls, such as network segmentation and access controls.
Recommended defensive actions
- Update Knot Resolver to version 6.4.1 or later
- Monitor systems for suspicious activity
- Implement network segmentation and access controls
- Conduct regular vulnerability assessments and penetration testing
- Review compensating controls for exposed systems while remediation is scheduled and verified
- Check relevant monitoring, detection, and logs for exposed assets that need extra review
- Track exceptions, retest remediated assets, and close the item only after evidence is documented
Evidence notes
The CVE record was published on 2026-07-25T01:16:26.423Z and was last modified on 2026-07-27T16:18:11.827Z. The NVD entry is currently in the 'Received' status. The vulnerability details are based on the information provided in the CVE record and the NVD entry. The source confidence is limited, and defenders should verify the affected scope and severity.
Official resources
AI-assisted PatchSiren debrief based on the supplied source corpus. The CVE record was published on 2026-07-25T01:16:26.423Z and has not been modified since then. The NVD entry is currently Received.