CVE-2026-123588
Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool
The recursive resolver in Hickory DNS (all versions of the hickory-recursor crate, and hickory-resolver 0.26.0 before 0.26.2) caches an empty connection pool when it follows a referral with no glue records and all queries for the name servers' IP addresses fail. An attacker able to spoof DNS responses can make these lookups fail, causing all subsequent queries for the affected zone to fail until the cache entry expires or is evicted.
Fixes and workarounds
No remediation reported in collected sources.
Missing remediation information is not evidence that no patch exists.
Affected products and versions
| Product | Versions | Authority |
|---|---|---|
| hickory-dns hickory-dns hickory-recursor
cargo |
≥ 0; ≤ 0.26.0-alpha.1 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
| hickory-dns hickory-dns hickory-resolver
cargo |
≥ 0.26.0; < 0.26.2 (affected, semver) 0.26.2 (unaffected, semver) Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 8.7 high |
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CNA: VulnCheck |
| 3.1 / 7.5 high |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H | CNA: VulnCheck |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-9px7-7m25-f6q2CNA: VulnCheck · vendor-advisory
- https://www.vulncheck.com/advisories/hickory-dns-recursive-resolver-denial-of-service-via-cached-empty-connection-poolCNA: VulnCheck · third-party-advisory
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