Quick answers
- Is CVE-2026-82717 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-82717 being exploited in the wild.
- How severe is CVE-2026-82717?
- 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-2026-82717?
- A patch was published on 2026-09-16: Unbound 1.26.1 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-82717 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-82717?
- 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 heap buffer overflow in Unbound's DNS packet handling, specifically triggered during CNAME synthesis when enforcing a max TTL value rewrite in the packet buffer. When a compression pointer references an overwritten value that invalidates a domain name, the error path fails to advance the buffer position correctly, allowing heap memory to be overwritten. The attack requires an upstream DNS response with specific packet structure; no authentication is needed. An attacker with the ability to send crafted DNS responses can corrupt heap memory, typically resulting in a crash, and under specific system configurations and compilation options may achieve remote code execution. Unbound 1.26.1 and patched versions of 1.26.0 address the vulnerability.
Affected products
- NLnet Labs Unbound up to and including 1.26.0
Timeline
- 2026-09-16: disclosed: CVE-2026-82717 published
- 2026-09-16: patched: Unbound 1.26.1 released with fix