CVE-2026-81634 NLnet Labs Unbound - Buffer Overflow

NLnet Labs Unbound <= 1.26.0 contains a heap buffer overflow caused by missing buffer length check for the first owner name during RRSet canonicalisation, letting malicious name servers or tampered responses cause memory corruption, exploit requires attacker to control or tamper DNS responses.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.48% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Buffer Overflow
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
16 September 2026
Updated
15 October 2026
Weakness
CWE-122

Vendor fix

Update to a version later than 1.26.0 or the latest available version.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

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