ISC BIND is affected by CVE-2015-5477, rated 7.5 (high). CISA lists it as a Known Exploited Vulnerability, added on 2026-10-08, which means attacks against it have been observed.
What the flaw is
The NIST National Vulnerability Database describes it as follows:
named in ISC BIND 9.x before 9.9.7-P2 and 9.10.x before 9.10.2-P3 allows remote attackers to cause a denial of service (REQUIRE assertion failure and daemon exit) via TKEY queries.
At a glance
| Field | Detail |
|---|---|
| CVE | CVE-2015-5477 |
| Affected product | ISC BIND |
| Weakness | CWE-19 |
| CVSS | 7.5 HIGH — CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| Added to CISA KEV | 2026-10-08 |
| Federal remediation due | 2026-10-11 |
| Known ransomware use | Unknown |
What defenders should do
- CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
- Patch: apply the fixed release from ISC; check the vendor advisory linked below for the exact versions.
- Inventory: identify every instance of ISC BIND, prioritising internet-facing ones.
- Hunt: review access and application logs on exposed instances for activity predating the patch, and treat unpatched internet-facing instances as potentially compromised.
