# CVE-2026-123572: hickory-dns denial of service in SVCB/HTTPS record parser

Source: https://junglewise.ai/threats/cve-2026-123572-hickory-dns-from-0-20-1-before-0-26-2-contains-a-denial-of  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-08. Updated: 2026-11-08  
License: CC BY 4.0 with a link back

CVE-2026-123572 · Severity: high · CVSS 7.5 · Published 2026-11-08

Hickory-dns is a DNS resolver library used to parse DNS records and zone files. A flaw in how it parses SVCB and HTTPS DNS record types causes the parser to crash when given malformed data, allowing attackers who can supply zone files to trigger denial of service and take the DNS service offline.

Technologies: [Hickory-Dns Hickory-Proto](https://junglewise.ai/threats/technologies/hickory-dns-hickory-proto). Vendors: [Hickory-Dns](https://junglewise.ai/threats/vendors/hickory-dns).

## Quick answers

**Is CVE-2026-123572 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-123572 being exploited in the wild.

**How severe is CVE-2026-123572?** High severity, with a CVSS score of 7.5, published 8 November 2026.

**Which products and versions are affected?** Hickory-Dns Hickory-Proto 0.20.1 through 0.26.1.

**Is there a fix for CVE-2026-123572?** Yes: fixed in 0.26.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-123572 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-123572?** Check whether you run Hickory-Dns Hickory-Proto at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in 0.26.2

## Technical details

The hickory-proto component panics when parsing malformed alpn (Application-Layer Protocol Negotiation) values in SVCB (RR type 64) and HTTPS (RR type 65) records, triggered by unbalanced quotes, consecutive commas, or invalid escape sequences. An attacker capable of supplying untrusted zone files can crash the parsing process. This is an input validation failure (CWE-1286) with network-based attack vector and no privileges required.

## Affected products

- hickory-dns hickory-proto 0.20.1 through 0.26.1

## Timeline

- 2026-09-03: disclosed
- 2026-11-08: advisory

## References

- [https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-hx8c-fjhc-hmf5](https://github.com/hickory-dns/hickory-dns/security/advisories/GHSA-hx8c-fjhc-hmf5)
- [https://www.vulncheck.com/advisories/hickory-dns-0.20.1-before-0.26.2-panic-dos-via-svcb-https-zone-parser](https://www.vulncheck.com/advisories/hickory-dns-0.20.1-before-0.26.2-panic-dos-via-svcb-https-zone-parser)

## Related threats

- [Hickory DNS hickory-proto denial of service in BinEncoder](https://junglewise.ai/threats/cve-2026-123608-hickory-dns-hickory-proto-from-0-3-1-before-0-26-1-contains-a)
- [Hickory DNS NSEC3 closest-encloser proof unbounded loop](https://junglewise.ai/threats/cve-2026-123607-hickory-dns-hickory-proto-0-25-0-alpha-3-through-0-25-2-and)
- [Hickory DNS DNSSEC validation bypass via RRSIG Signer's Name](https://junglewise.ai/threats/cve-2026-123605-hickory-dns-hickory-proto-0-1-through-0-25-0-alpha-3-and-hickory)
- [Hickory DNS IPv4-mapped IPv6 canonicalization bypass](https://junglewise.ai/threats/cve-2026-123603-hickory-proto-and-hickory-resolver-0-26-0-before-0-26-2-hickory)
- [Hickory DNS NSEC3 comparison operator inversion](https://junglewise.ai/threats/cve-2026-123601-hickory-dns-hickory-proto-0-25-0-through-0-26-0-alpha-1-and)