CVE-2026-32936
CoreDNS DoH GET oversized dns= query parameter causes pre-validation CPU and memory amplification
Impact
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 | Affected | Fixed in |
|---|---|---|---|
| go | github.com/coredns/coredns | < 1.14.3 | 1.14.3 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Coredns.Io | Coredns | before 1.14.3 |