CVE-2026-81634
Possible heap buffer overflow during DNSSEC canonicalization
- State
- Published
- Severity
- 7.5 High
- Published
- Sep 16, 2026
- Updated
- Sep 16, 2026
- Reserved
- Sep 7, 2026
Description
In NLnet Labs Unbound up to and including 1.26.0, a 255 length query name with a large TCP response can lead to a heap buffer overflow during the RRSet canonicalisation routine. This is caused by missing to add the first owner name into the buffer length check. A malicious actor operating a malicious name server or tampering with an incoming response to Unbound (canonicalisation happens before DNSSEC validation), can trigger the vulnerability.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | NLnet Labs |
Weaknesses
- CWE-122 Heap-based Buffer Overflow
Affected Products
| Product | Versions |
|---|---|
UnboundNLnet Labs |
|
References
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