CVE-2026-32936
CVE-2026-32936 is a Uncontrolled Resource Consumption vulnerability in github.com/coredns/coredns. O3 Security confirms whether CVE-2026-32936 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
CoreDNS DoH GET path missing size validation causes CPU and memory amplification
Real-World Exposure
github.com/coredns/corednsReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
CoreDNS is a DNS server that chains plugins. In versions prior to 1.14.3, the DNS-over-HTTPS (DoH) GET path accepts oversized dns= query parameter values and performs URL query parsing, base64 decoding, and DNS message unpacking before rejecting the request. Unlike the POST path, which applies a bounded read via http.MaxBytesReader limited to 65536 bytes, the GET path has no equivalent size validation before expensive processing. A remote, unauthenticated attacker can repeatedly send oversized DoH GET requests to force high CPU usage, large transient memory allocations, and elevated garbage-collection pressure, leading to denial of service. This issue has been fixed in version 1.14.3.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/coredns/coredns | all versions | 1.14.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/coredns/coredns. 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 github.com/coredns/coredns to 1.14.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-32936 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 CVE-2026-32936 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 CVE-2026-32936. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-32936 in your dependencies?
O3 detects CVE-2026-32936 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.