Memory Amplification Vulnerability in Hickory DNS by Hickory Technologies
CVE-2026-123570

8.7HIGH

Key Information:

Vendor

Hickory-dns

Status
Hickory-dns
Vendor
CVE Published:
8 November 2026

What is CVE-2026-123570?

The hickory-proto DNS parser in Hickory DNS versions 0.18 to 0.26.2 has a critical flaw where it preallocates record vectors based on values derived from untrusted header fields (ANCOUNT, NSCOUNT, and ARCOUNT). Attackers can exploit this vulnerability by sending a specially crafted UDP datagram with maximum header values (65535), leading to excessive memory allocation of approximately 18MB per datagram. This can result in a denial of service, overwhelming the server's resources and impacting availability.

Affected Version(s)

hickory-dns 0.18 < 0.26.2

hickory-dns 0.26.2

References

https://github.com/hickory-dns/hickory-dns/security/advis...
vendor-advisory
https://www.vulncheck.com/advisories/hickory-dns-from-0.1...
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
None
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

jpds
.