Answer in brief
CVE-2026-123603 records a Medium severity (CVSS 6.9) vulnerability in Hickory DNS Missing IPv4-Mapped IPv6 Canonicalization Access Control Bypass. The current sources do not mark it as known exploited. The current feed maps hickory-dns/hickory-dns (generic), hickory-dns/hickory-dns (generic), hickory-dns/hickory-dns (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 6.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps hickory-dns/hickory-dns (generic), hickory-dns/hickory-dns (generic), hickory-dns/hickory-dns (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| hickory-dns/hickory-dnsgeneric | >=0.25.0-alpha.3 <=0.26.0-alpha.1 | Not reported |
| hickory-dns/hickory-dnsgeneric | >=0.26.0 <0.26.2 | 0.26.2 |
| hickory-dns/hickory-dnsgeneric | >=0.25.0-alpha.1 <0.26.2 | 0.26.2 |
Published upstream
Nov 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 8, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 8, 2026
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.
Quoted source text, attributed separately from HOL analysis.