CVSS 4.0
8.7 highCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NCVE-2026-123588 Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool
High (8.7) in hickory-dns hickory-dns. EPSS 0.3% estimated probability of exploitation activity in the next 30 days.
On this page
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.
Severity
CVSS 3.1
7.5 highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- EPSS
- 0.3% estimated probability of exploitation activity in the next 30 days; 28th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CISA's assessment (SSVC)
- Exploitation: none · Automatable: yes · Technical impact: partial, assessed 2026-11-12. From CISA's Vulnrichment in the CVE List: whether it is exploited, whether exploiting it can be automated, and how much control it gives.
- CWE
- CWE-754 Improper Check for Unusual or Exceptional Conditions
- OWASP Top 10
- A10:2025 Mishandling of Exceptional Conditions
- Published
- Modified
- Assigned by
- VulnCheck (CNA)
- NVD analysis
- Deferred: the NVD does not plan to analyze it
- Record from
- the NVD, synced
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Affected
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| hickory-dns | through 0.26.0-alpha.1 |
| hickory-dns | from 0.26.0 before 0.26.2 |
Fix and patched versions
Linux distributions
| Distribution | Release | Package | Fixed in | Advisory |
|---|---|---|---|---|
| Debian | 13 | rust-hickory-recursor, rust-hickory-resolver | no fix listed | DEBIAN-CVE-2026-123588 |
| Debian | 14 | rust-hickory-resolver | 0.26.3-1 | DEBIAN-CVE-2026-123588 |
| Ubuntu | 24.04:LTS | rust-hickory-resolver | no fix listed | UBUNTU-CVE-2026-123588 |
| Ubuntu | 26.04:LTS, 26.10 | rust-hickory-recursor, rust-hickory-resolver | no fix listed | UBUNTU-CVE-2026-123588 |
From the distributions' data via OSV.dev: the Debian Security Tracker; Ubuntu Security Notices © Canonical Ltd., CC BY-SA 4.0. Modified: reformatted and linked to CVE records. Credits. On the distributions' own pages: Debian · Ubuntu.
History
- The NVD deferred its analysis
Changes since this site first stored the record. The same for every record: /api/public/changes.