Resource exhaustion in Coredns
CVE-2026-32936
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.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.007 (49.7th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
Affected products
- Coredns — versions < 1.14.3
- Coredns.io Coredns
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-32936?
- CVE-2026-32936 is a high-severity vulnerability in Coredns, classified under Uncontrolled Resource Consumption. CVSS score: 7.5/10. Published 2026-05-05.
- How severe is CVE-2026-32936?
- High severity. CVSS v3 base score is 7.5 out of 10.