Description
Hickory DNS 0.25.0-alpha.3 through 0.25.2 contains a query amplification vulnerability in its recursive resolver, which mishandles cyclic sibling name server referrals that lack glue records. Attackers controlling two zones whose name servers reference each other without glue records can make the recursor loop, sending many upstream queries, amplified further by zero-TTL NS records.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| hickory-dns | hickory-dns | 0.25.0-alpha.3 – ≤ 0.25.2, < 0.26.2 | 0.26.2 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | rust-hickory-resolver | 0.26.3-1 | — |
| Debian 13 | rust-hickory-recursor +1 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | rust-hickory-recursor +1 | No fix yet | — |
| Ubuntu 26.04 LTS | rust-hickory-recursor +1 | No fix yet | — |
| Ubuntu 24.04 LTS | rust-hickory-resolver | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| crates.io | hickory-recursor | >= 0.25.0-alpha.3 | — | RUSTSEC-2026-0522 |
| crates.io | hickory-resolver | >= 0.26.0-beta.1, < 0.26.2 | 0.26.2 | RUSTSEC-2026-0516 |
References
- GitHub Security Advisory (GHSA-cx5j-p54p-q756) vendor-advisory
- VulnCheck Advisory: Hickory DNS 0.25.0-alpha.3 through 0.25.2 Query Amplification via Cyclic Referrals third-party-advisory