Description
Hickory DNS hickory-proto through 0.26.0-alpha.1 and hickory-net 0.26.0-beta.1 before 0.26.2 contain a DNSSEC validation flaw in the validating recursor's NSEC handler that accepts parent-side ancestor-delegation NSEC records as proof of nonexistence for names below the zone cut. An on-path attacker, rogue parent nameserver, or attacker winning a port and TXID race can deliver one forged NXDOMAIN response built from genuinely signed parent NSEC records, causing authenticated denial of existing child-zone names cached for the negative TTL.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| hickory-dns | hickory-dns | ≤ 0.26.0-alpha.1, 0.26.0-beta.1 – < 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-net | 0.26.3-1 | — |
| Debian 14 | rust-hickory-proto | No fix yet | — |
| Debian 13 | rust-hickory-proto | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | rust-hickory-net +1 | No fix yet | — |
| Ubuntu 26.04 LTS | rust-hickory-proto | No fix yet | — |
| Ubuntu 24.04 LTS | rust-hickory-proto | No fix yet | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | netavark | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| crates.io | hickory-net | >= 0.0.0-0, < 0.26.2 | 0.26.2 | RUSTSEC-2026-0539 |
| crates.io | hickory-proto | >= 0.0.0-0, < 0.26.0-beta.1 | 0.26.0-beta.1 | RUSTSEC-2026-0530 |