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CVE-2026-123603— Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass

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.

在 和 0.26.0 至 0.26.2 之前的版本、 0.25.0-alpha.1 至 0.26.2 之前的版本，以及 0.25.0-alpha.3 至 0.26.0-alpha.1 的版本中，系统在检查 、 或 规则时，未能对 IPv4 映射的 IPv6 地址进行规范化处理。攻击者可利用 IPv4 映射地址绕过应答过滤机制，触发对已被禁止的域名服务器的查询，或从被拒绝的客户端访问运行在双栈 IPv6 套接字上的 库部署实例。

CVSS 6.5 · Medium

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application
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I. Basic Information for CVE-2026-123603

Vulnerability Information
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Vulnerability Title
Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
hickory-proto and hickory-resolver 0.26.0 before 0.26.2, hickory-server 0.25.0-alpha.1 before 0.26.2, and hickory-recursor 0.25.0-alpha.3 through 0.26.0-alpha.1 fail to canonicalize IPv4-mapped IPv6 addresses when checking deny_answers, deny_server, or AccessControlSet rules. Attackers can use IPv4-mapped addresses to evade answer filtering, trigger queries to denied nameservers, or reach hickory-server library deployments on dual-stack IPv6 sockets from denied clients.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
访问控制不恰当
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
hickory-dns hickory-dns 0.25.0-alpha.3 ~ 0.26.0-alpha.1 -
hickory-dns hickory-dns 0.26.0 ~ 0.26.2 -
hickory-dns hickory-dns 0.26.0 ~ 0.26.2 -
hickory-dns hickory-dns 0.25.0-alpha.1 ~ 0.26.2 -

II. Public POCs for CVE-2026-123603

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III. Intelligence Information for CVE-2026-123603

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Other References for CVE-2026-123603 (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-2026-123588 7.5 HIGH Hickory DNS Recursive Resolver Denial of Service via Cached Empty Connection Pool
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-2026-123601 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-284