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CVE-2026-123588— Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool

Quick assessment

Affected
hickory-dns hickory-dns
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Hickory DNS 中的递归解析器（涵盖 crate 的所有版本，以及 0.26.0 至 0.26.2 之前的版本）存在以下问题：当解析器跟随一条缺乏粘合记录（glue records）的转介（referral）响应，且所有针对该名称服务器 IP 地址的查询均失败时，它会缓存一个空的连接池。能够伪造 DNS 响应的攻击者可利用此机制使这些查询失败，从而导致受影响区域的所有后续查询在缓存条目过期或被驱逐之前持续失败。

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-123588

Vulnerability Information
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Vulnerability Title
Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
对因果或异常条件的不恰当检查
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
hickory-dns hickory-dns 0 ~ 0.26.0-alpha.1 -
hickory-dns hickory-dns 0.26.0 ~ 0.26.2 -

II. Public POCs for CVE-2026-123588

# POC Description Source Link Shenlong Link
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III. Intelligence Information for CVE-2026-123588

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Other References for CVE-2026-123588 (2)

Same Patch Batch · hickory-dns · 2026-11-08 · 39 CVEs total

CVE-2026-123595 8.8 HIGH Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC3
CVE-2026-123596 8.8 HIGH Hickory DNS through 0.26.0-alpha.1 DNSSEC Validation Bypass via Ancestor-Delegation NSEC
CVE-2026-123605 8.8 HIGH Hickory DNS through 0.25.0-alpha.3 DNSSEC Validation Bypass via RRSIG Signer's Name
CVE-2026-123570 7.5 HIGH Hickory DNS from 0.18 before 0.26.2 Memory Amplification DoS via RR Counts
CVE-2026-123572 7.5 HIGH Hickory-dns 0.20.1 before 0.26.2 Panic DoS via SVCB/HTTPS Zone Parser
CVE-2026-123575 7.5 HIGH Hickory DNS before 0.26.2 DoH Memory Exhaustion via Incomplete Request Bodies
CVE-2026-123571 7.5 HIGH Hickory DNS from 0.26.0 before 0.26.2 Panic via TSIG RDATA Decoding
CVE-2026-123577 7.5 HIGH Hickory DNS 0.24.0 before 0.26.2 DoH Unbounded Request Body Denial of Service
CVE-2026-123574 7.5 HIGH Hickory DNS 0.24.0 before 0.26.2 Denial of Service via Zone File Parser
CVE-2026-123604 7.5 HIGH Hickory DNS 0.26.0-beta.1 before 0.26.2 Resource Exhaustion DoS via NameServerPool::try_se
CVE-2026-123576 7.5 HIGH Hickory DNS 0.24.0 through 0.26.1 Memory Exhaustion via DNS-over-QUIC Requests
CVE-2026-123573 7.5 HIGH hickory-dns from 0.20.1 before 0.26.2 Panic in SVCB/HTTPS Zone File Parser
CVE-2026-123606 7.5 HIGH Hickory-DNS Recursor 0.25.0-alpha.3 through 0.25.2 Glueless-NS Referral Amplification
CVE-2026-123607 7.5 HIGH Hickory DNS NSEC3 Closest-Encloser Proof Unbounded Loop Denial of Service
CVE-2026-123580 7.5 HIGH Hickory-DNS 0.26.0-beta.1 before 0.26.2 DNSSEC Nonexistence Proof Forgery via NSEC3
CVE-2026-123608 7.5 HIGH Hickory DNS hickory-proto 0.3.1 before 0.26.1 CPU Exhaustion via BinEncoder Name Compressi
CVE-2026-123586 7.5 HIGH Hickory DNS 0.25.0-alpha.3 through 0.25.2 Query Amplification via Cyclic Referrals
CVE-2026-123587 6.8 MEDIUM Hickory-DNS 0.26.0 before 0.26.2 DNSSEC Nonexistence Forgery via Wraparound NSEC
CVE-2026-123603 6.5 MEDIUM Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass
CVE-2026-123601 6.5 MEDIUM Hickory DNS 0.26.0-beta.1 before 0.26.2 NSEC3 Proof of Nonexistence Forgery

Showing top 20 of 39 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: hickory-dns
Same vendor: hickory-dns
Same weakness: CWE-754