CVE-2026-12617: CWE-617 Reachable Assertion in ISC BIND 9
CVE-2026-12617 is a vulnerability in ISC BIND 9 that causes unexpected program termination (crash) due to reachable assertions triggered by specific query response ordering and content involving CNAME, DNAME, and A records. The issue affects multiple BIND 9 versions and can cause the named DNS server process to quit unexpectedly.
AI Analysis
Technical Summary
This vulnerability arises when a client queries for a DNAME and an A record below the DNAME, or a CNAME and an A record for the same name, and the authoritative server responds positively to the A record query but delays the DNAME or CNAME response, later responding negatively or with a self-referential CNAME. Under these conditions, the named process in ISC BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, and their respective S1 variants may terminate unexpectedly due to a reachable assertion failure (CWE-617). This results in denial of service by crashing the DNS resolver.
Potential Impact
The impact is denial of service caused by unexpected termination of the named DNS server process. There is no indication of confidentiality or integrity loss. The vulnerability can be triggered remotely by sending crafted DNS queries that exploit the timing and content of responses involving CNAME, DNAME, and A records.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is indicated in the provided data. Until a patch is available, consider monitoring for unusual named process crashes and controlling access to the DNS resolver to limit exposure.
CVE-2026-12617: CWE-617 Reachable Assertion in ISC BIND 9
Description
CVE-2026-12617 is a vulnerability in ISC BIND 9 that causes unexpected program termination (crash) due to reachable assertions triggered by specific query response ordering and content involving CNAME, DNAME, and A records. The issue affects multiple BIND 9 versions and can cause the named DNS server process to quit unexpectedly.
CVSS v3.1
Score 7.5high
Affected software
pkg:github/isc/bind9Run on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
This vulnerability arises when a client queries for a DNAME and an A record below the DNAME, or a CNAME and an A record for the same name, and the authoritative server responds positively to the A record query but delays the DNAME or CNAME response, later responding negatively or with a self-referential CNAME. Under these conditions, the named process in ISC BIND 9 versions 9.18.0 through 9.18.50, 9.20.0 through 9.20.24, and their respective S1 variants may terminate unexpectedly due to a reachable assertion failure (CWE-617). This results in denial of service by crashing the DNS resolver.
Potential Impact
The impact is denial of service caused by unexpected termination of the named DNS server process. There is no indication of confidentiality or integrity loss. The vulnerability can be triggered remotely by sending crafted DNS queries that exploit the timing and content of responses involving CNAME, DNAME, and A records.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or temporary workaround is indicated in the provided data. Until a patch is available, consider monitoring for unusual named process crashes and controlling access to the DNS resolver to limit exposure.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-06-18T13:52:43.335Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a60d93c9c2644c7f8363a08
Added to database: 07/22/2026, 14:52:44 UTC
Last enriched: 07/22/2026, 15:07:37 UTC
Last updated: 07/22/2026, 15:57:23 UTC
Views: 5
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