Quick answers
- Is This vulnerability exploited in the wild?
- No. Junglewise Threat Intelligence has no report of This vulnerability being exploited in the wild.
- How severe is This vulnerability?
- High severity, published 5 October 2026.
- Which products and versions are affected?
- hickory-resolver (crates.io) >= 0.26.0-beta.1, < 0.26.2; Hickory-Dns Hickory-Resolver >= 0.26.0-beta.1, < 0.26.2.
- Is there a fix for This vulnerability?
- Yes: fixed in 0.26.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is This vulnerability attacked?
- It is attacked over the network.
- Am I affected?
- Check whether you run hickory-resolver (crates.io) or Hickory-Dns Hickory-Resolver 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.
How to fix
- Fixed in: 0.26.2
Technical details
The vulnerability is an unbounded retry loop in the NameServerPool::try_send function: when a TC (truncated) bit is set in an upstream DNS response, the resolver re-queues the request to the same nameserver with TCP instead of UDP, but the retry logic lacks transport state tracking and iteration limits. An authoritative server responding with TC=1 on every transport keeps the resolver spinning until the 5-second per-request wall-clock deadline expires, consuming resources. The attack requires network-level access to respond as a nameserver (MITM or direct query routing).
Affected products
- hickory-dns hickory-resolver >= 0.26.0-beta.1, < 0.26.2
Timeline
- 2026-09-03: disclosed
- 2026-10-05: advisory