Summary
hickory-proto: NSEC3 closest-encloser proof validation enters unbounded loop on cross-zone responses
The NSEC3 closest-encloser proof validation in hickory-proto's (0.25.0-alpha.3 ... 0.25.2) and hickory-net's (0.26.0-alpha.1 .. 0.26.0) DnssecDnsHandle walks from the QNAME up to the SOA owner name, building a list of candidate encloser names. The iterator used assumes the QNAME is a descendant of the SOA owner, terminating only when the current candidate equals the SOA name. When the SOA in a response's authority section is not an ancestor of the QNAME, the loop stalls at the DNS root and never terminates, repeatedly calling Name::base_name() and pushing newly allocated Name and hashed-name entries into the candidate Vec.
The bug is reachable by any caller of DnssecDnsHandle, including the resolver, recursor, and client, when built with the dnssec-ring or dnssec-aws-lc-rs feature and configured to perform DNSSEC validation. It is triggered while validating a NoData or NXDomain response whose authority section contains an SOA record from a zone other than an ancestor of the QNAME, on a code path that requires NSEC3 closest-encloser proof. In practice this can be reached through an insecure CNAME chain that crosses zone boundaries into a DNSSEC-signed zone returning NoData, but the minimum condition is just a mismatched SOA owner on a response requiring NSEC3 validation.
A debug_assert_ne!(name, Name::root()) guards the loop body, so debug builds abort with a panic on the first iteration past the root. Release builds compile the assertion out and run the loop unbounded, allocating until the process exhausts available memory. A reachable upstream attacker who can return such a response can therefore crash a debug build or exhaust memory on a release build, for the affected configurations.
The affected code was migrated from hickory-proto to hickory-net as part of the 0.26.0 release. Hickory DNS recommends that all affected users update to hickory-net 0.26.1 for the fix.
Reporter
David Cook, ISRG
Impact
Affected versions
Security releases
Kodem intelligence
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Frequently Asked Questions
- What is GHSA-3V94-MW7P-V465? GHSA-3V94-MW7P-V465 is a high-severity security vulnerability in hickory-proto (rust), affecting versions >= 0.25.0-alpha.3, <= 0.25.2. It is fixed in 0.26.1.
- Which packages are affected by GHSA-3V94-MW7P-V465?
hickory-proto(rust) (versions >= 0.25.0-alpha.3, <= 0.25.2)hickory-net(rust) (versions >= 0.26.0-alpha.1, <= 0.26.0)
- Is there a fix for GHSA-3V94-MW7P-V465? Yes. GHSA-3V94-MW7P-V465 is fixed in 0.26.1. Upgrade to this version or later.
- Is GHSA-3V94-MW7P-V465 exploitable, and should I be worried? Whether GHSA-3V94-MW7P-V465 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether GHSA-3V94-MW7P-V465 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix GHSA-3V94-MW7P-V465? Upgrade
hickory-netto 0.26.1 or later.