EUVD-2026-80778
GHSA-m66j-g9q7-jxjg
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Network-reachable resolver crash with no privileges or interaction (AV:N/AC:L/PR:N/UI:N); availability-only via program exit, no C/I impact, so A:H and 7.5.
Primary rating from Vendor (isc).
CVSS VectorNVD
Lifecycle Timeline
4DescriptionNVD
If a BIND resolver sends a query for a DNSSEC-signed authoritative zone, and the authoritative server replies with a valid wildcard answer and signed NSEC3 proof, followed by an unsigned NSEC at the same owner name, it will trigger an unexpected program exit. This issue affects BIND 9 versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, 9.11.3-S1 through 9.18.50-S1, and 9.20.9-S1 through 9.20.27-S1.
AnalysisAI
Denial of service in ISC BIND 9 recursive resolvers affects versions 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and the subscription builds 9.11.3-S1 through 9.18.50-S1 and 9.20.9-S1 through 9.20.27-S1. A validating resolver can be crashed when an authoritative server it queries returns a valid wildcard answer with a signed NSEC3 proof immediately followed by an unsigned NSEC record at the same owner name, causing an unexpected program exit via a reachable assertion (CWE-617). …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | The victim must be a recursive BIND 9 resolver performing DNSSEC validation of a signed zone. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | This is a genuine remote-triggerable denial-of-service in ISC BIND 9, one of the most widely deployed DNS server implementations. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | Vendor-released patches are BIND 9.20.29 and 9.21.26 (downloads at https://downloads.isc.org/isc/bind9/9.20.29 and https://downloads.isc.org/isc/bind9/9.21.26), with the advisory at https://kb.isc.org/docs/cve-2026-80274. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory every ISC BIND 9 recursive resolver in the estate, confirm which listed branches are present (9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, plus subscription builds 9.11.3-S1 through 9.18.50-S1 and 9.20.9-S1 through 9.20.27-S1), and verify that resolver health checks, automatic restart supervision, and secondary/forwarder failover are functioning so that any crash is detected and absorbed rather than becoming a resolution outage; identify which resolvers accept queries from the general internet or serve as the sole resolver for a business-critical segment and treat those as the immediate priority. …
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Same weakness CWE-617 – Reachable Assertion
View allSame technique Denial Of Service
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External POC / Exploit Code
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