Summary
hickory-resolver: Unbounded TC-retry loop in NameServerPool::try_send (resource-exhaustion DoS)
When the hickory-resolver name server pool implementation receives an upstream response with the TC (truncated) header bit set, it re-queues the request to the same nameserver to retry with UDP transport disabled. However, the retry arm never inspects the transport that just answered and carries no iteration counter. An authoritative server that sets TC=1 on every available transport keeps the resolver spinning on one persistent TCP connection until the 5s per-request wall-clock deadline expires.
Reporter
Qifan Zhang, Palo Alto Networks
Impact
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
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Frequently Asked Questions
- What is GHSA-6W6G-HM98-MHGM? GHSA-6W6G-HM98-MHGM is a high-severity uncontrolled resource consumption vulnerability in hickory-resolver (rust), affecting versions >= 0.26.0-beta.1, < 0.26.2. It is fixed in 0.26.2. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of hickory-resolver are affected by GHSA-6W6G-HM98-MHGM? hickory-resolver (rust) versions >= 0.26.0-beta.1, < 0.26.2 is affected.
- Is there a fix for GHSA-6W6G-HM98-MHGM? Yes. GHSA-6W6G-HM98-MHGM is fixed in 0.26.2. Upgrade to this version or later.
- Is GHSA-6W6G-HM98-MHGM exploitable, and should I be worried? Whether GHSA-6W6G-HM98-MHGM 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-6W6G-HM98-MHGM 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-6W6G-HM98-MHGM? Upgrade
hickory-resolverto 0.26.2 or later.