CVE-2026-77119: CWE-346 Origin Validation Error in ISC BIND 9
A validly signed NSEC3 from an unrelated sibling zone may be accepted as an insecurity proof, downgrading a secure delegation and letting a forged unsigned answer through. 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.
AI Analysis
Technical Summary
This vulnerability (CWE-346: Origin Validation Error) in ISC BIND 9 involves improper validation of NSEC3 records used in DNSSEC. Specifically, a validly signed NSEC3 record from an unrelated sibling zone can be accepted as an insecurity proof, which downgrades a secure delegation and permits a forged unsigned DNS response to be accepted. This undermines DNSSEC's integrity guarantees. The affected versions include 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their S1 variants within these ranges.
Potential Impact
The vulnerability allows an attacker to bypass DNSSEC validation by exploiting origin validation errors, potentially enabling forged unsigned DNS answers to be accepted. This compromises the integrity of DNS responses but does not affect confidentiality or availability. The CVSS score of 5.9 (medium severity) reflects the moderate impact due to the requirement for network access and high attack complexity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor ISC advisories for updates and apply patches once available. Until then, consider DNSSEC validation policies and network controls to limit exposure.
CVE-2026-77119: CWE-346 Origin Validation Error in ISC BIND 9
Description
A validly signed NSEC3 from an unrelated sibling zone may be accepted as an insecurity proof, downgrading a secure delegation and letting a forged unsigned answer through. 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.
CVSS v3.1
Score 5.9medium
Affected software
ISC
BIND 9
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 (CWE-346: Origin Validation Error) in ISC BIND 9 involves improper validation of NSEC3 records used in DNSSEC. Specifically, a validly signed NSEC3 record from an unrelated sibling zone can be accepted as an insecurity proof, which downgrades a secure delegation and permits a forged unsigned DNS response to be accepted. This undermines DNSSEC's integrity guarantees. The affected versions include 9.11.0 through 9.18.50, 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and their S1 variants within these ranges.
Potential Impact
The vulnerability allows an attacker to bypass DNSSEC validation by exploiting origin validation errors, potentially enabling forged unsigned DNS answers to be accepted. This compromises the integrity of DNS responses but does not affect confidentiality or availability. The CVSS score of 5.9 (medium severity) reflects the moderate impact due to the requirement for network access and high attack complexity.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. No official fix or patch links are provided in the available data. Users should monitor ISC advisories for updates and apply patches once available. Until then, consider DNSSEC validation policies and network controls to limit exposure.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- isc
- Date Reserved
- 2026-08-20T12:48:33.514Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6aaaa87255bf5e2cf5bb988c
Added to database: 09/16/2026, 14:32:18 UTC
Last enriched: 09/16/2026, 14:47:06 UTC
Last updated: 09/17/2026, 00:17:16 UTC
Views: 8
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