GHSA-37wc-h8xc-5hc4
Hickory DNS's DNSSEC validation may accept broken authentication chains
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Blast Radius
hickory-protoReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
Summary
The DNSSEC validation routines treat entire RRsets of DNSKEY records as trusted once they have established trust in only one of the DNSKEYs. As a result, if a zone includes a DNSKEY with a public key that matches a configured trust anchor, all keys in that zone will be trusted to authenticate other records in the zone. There is a second variant of this vulnerability involving DS records, where an authenticated DS record covering one DNSKEY leads to trust in signatures made by an unrelated DNSKEY in the same zone.
Details
verify_dnskey_rrset() will return Ok(true) if any record's public key matches a trust anchor. This results in verify_rrset() returning a Secure proof. This ultimately results in successfully verifying a response containing DNSKEY records. verify_default_rrset() looks up DNSKEY records by calling handle.lookup(), which takes the above code path. There's a comment following this that says "DNSKEYs were already validated by the inner query in the above lookup", but this is not the case. To fully verify the whole RRset of DNSKEYs, it would be necessary to check self-signatures by the trusted key over the other keys. Later in verify_default_rrset(), verify_rrset_with_dnskey() is called multiple times with different keys and signatures, and if any call succeeds, then its Proof is returned.
Similarly, verify_dnskey_rrset() returns Ok(false) if any DNSKEY record is covered by a DS record. A comment says "If all the keys are valid, then we are secure", but this is only checking that one key is authenticated by a DS in the parent zone's delegation point. This time, after control flow returns to verify_rrset(), it will call verify_default_rrset(). The special handling for DNSKEYs in verify_default_rrset() will then call verify_rrset_with_dnskey() using each KSK DNSKEY record, and if one call succeeds, return its Proof. If there are multiple KSK DNSKEYs in the RRset, then this leads to another authentication break. We need to either pass the authenticated DNSKEYs from the DS covering check to the RRSIG validation, or we need to perform this RRSIG validation of the DNSKEY RRset inside verify_dnskey_rrset() and cut verify_default_rrset() out of DNSKEY RRset validation entirely.
PoC
The proof of concepts have been integrated into the conformance test suite, as resolver::dnssec::scenarios::bogus::bogus_zone_plus_trust_anchor_dnskey and resolver::dnssec::scenarios::bogus::bogus_zone_plus_ds_covered_dnskey.
Impact
This impacts Hickory DNS users relying on DNSSEC verification in the client library, stub resolver, or recursive resolver.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | hickory-proto | ≥ 0.8.0&&< 0.24.3 | 0.24.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for hickory-proto. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update hickory-proto to 0.24.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-37wc-h8xc-5hc4 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-37wc-h8xc-5hc4 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-37wc-h8xc-5hc4. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-37wc-h8xc-5hc4 in your dependencies?
O3 detects GHSA-37wc-h8xc-5hc4 across crates.io dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.