Medium severity · published Sep 16, 2026
CVE-2026-77119
NSEC3 insecure-referral proof can use unrelated cached NSEC3 RRsets
5.9
CVSS
0.2%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
High
Availability
None
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 13% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
B9
BIND 9 · ISC
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; 9.20.9-S1 through 9.20.27-S1 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-77119
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-77119
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.20.29
downloads.isc.org
https://downloads.isc.org/isc/bind9/9.21.26
kb.isc.org
https://kb.isc.org/docs/cve-2026-77119
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