Quick answers
- Is CVE-2026-81642 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-81642 being exploited in the wild.
- How severe is CVE-2026-81642?
- Critical severity, with a CVSS score of 9.8, published 16 September 2026.
- Which products and versions are affected?
- NLnet Labs Unbound up to and including 1.26.0.
- Is there a fix for CVE-2026-81642?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-81642 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-81642?
- Check whether you run NLnet Labs Unbound at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a buffer overflow in the DNSSEC validator's DNSKEY digestion logic. A specially crafted DNSKEY record containing an owner compression pointer to its own RDATA section can overflow the digest buffer during decompression, before a capacity check is performed. The attack requires network reachability to the vulnerable Unbound instance and control of a malicious DNS zone; an attacker can trigger the overflow by querying the resolver for records in their controlled zone. Exploitation enables both denial of service and remote code execution through attacker-controlled data. Patched versions (Unbound 1.26.1 and later) include proper capacity validation after decompression to prevent the overflow.
Affected products
- NLnet Labs Unbound up to and including 1.26.0
Timeline
- 2026-09-16: disclosed