PT-2026-37095 · Coredns · Coredns
CVSS v4.0
8.7
High
| Vector | AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
Name of the Vulnerable Software and Affected Versions
CoreDNS versions prior to 1.14.3
Description
CoreDNS is a DNS server that chains plugins. A denial-of-service issue exists in the DNS-over-HTTPS (DoH) GET path because it lacks early size validation for requests. A remote, unauthenticated attacker can send oversized requests to the '/dns-query' endpoint using the
dns query parameter. The server performs expensive operations—including URL query parsing, base64 decoding via the base64ToMsg() function, and DNS message unpacking—before rejecting the request with a 400 Bad Request error.This process forces high CPU usage, large transient memory allocations, and elevated garbage-collection pressure, which can lead to degraded throughput and responsiveness or a complete denial of service, particularly on memory-constrained deployments.
Recommendations
Update to version 1.14.3.
As a temporary workaround, restrict access to the '/dns-query' endpoint or implement a web application firewall (WAF) to limit the size of GET request targets and the
dns parameter.Exploit
Fix
DoS
Resource Exhaustion
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Weakness Enumeration
Related Identifiers
Affected Products
Coredns