# CVE-2026-32936: CoreDNS denial of service via oversized DoH GET requests

Source: https://junglewise.ai/threats/cve-2026-32936-coredns-denial-of-service-via-oversized-doh-get-requests  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-05-05. Updated: 2026-07-25  
License: CC BY 4.0 with a link back

CVE-2026-32936 · Severity: high · CVSS 7.5 · Published 2026-05-05

CoreDNS is a widely used DNS server that helps translate human-readable domain names into IP addresses. A vulnerability in its DNS-over-HTTPS (DoH) feature allows an unauthenticated attacker to overwhelm the server by sending specially crafted, oversized requests. This can lead to high CPU and memory usage, potentially causing the service to slow down or crash, which would disrupt internet connectivity for users relying on that server.

Technologies: [CoreDNS](https://junglewise.ai/threats/technologies/coredns), [github.com/coredns/coredns (Go)](https://junglewise.ai/threats/technologies/github-com-coredns-coredns). Vendors: [CoreDNS](https://junglewise.ai/threats/vendors/coredns), [Go](https://junglewise.ai/threats/vendors/go).

## Quick answers

**Is CVE-2026-32936 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-32936 being exploited in the wild.

**How severe is CVE-2026-32936?** High severity, with a CVSS score of 7.5, published 5 May 2026.

**Which products and versions are affected?** CoreDNS < 1.14.3; github.com/coredns/coredns (Go) < 1.14.3, SEMVER:introduced=0,fixed=1.14.3.

**Is there a fix for CVE-2026-32936?** Yes. github.com/coredns/coredns (Go): upgrade to 1.14.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-32936 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-32936?** Check whether you run CoreDNS or github.com/coredns/coredns (Go) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- github.com/coredns/coredns (Go): upgrade to 1.14.3 or later

  ```sh
  go get github.com/coredns/coredns@v1.14.3
  ```


## Technical details

A denial-of-service (DoS) vulnerability exists in CoreDNS versions prior to 1.14.3 within the DNS-over-HTTPS (DoH) GET request handler. While the POST path implements a bounded read using http.MaxBytesReader (limited to 64KB), the GET path lacks equivalent size validation for the 'dns=' query parameter. An unauthenticated remote attacker can send oversized base64-encoded DNS queries, forcing the server to perform URL unescaping, base64 decoding, and DNS message unpacking before the request is eventually rejected. This results in uncontrolled resource consumption (CWE-400), characterized by high CPU usage, large transient memory allocations, and increased garbage collection pressure. The issue is resolved in version 1.14.3 by implementing proper size checks on the GET path.

## Affected products

- CoreDNS CoreDNS < 1.14.3

## Identifiers

- CVE-2026-32936
- GHSA-63cw-r7xf-jmwr
- GO-2026-5164

## Timeline

- 2026-04-22: patched: Version 1.14.3 released
- 2026-04-25: advisory: GitHub Security Advisory GHSA-63cw-r7xf-jmwr published
- 2026-05-05: disclosed: CVE-2026-32936 published to NVD

## References

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

## Related threats

- [CoreDNS RFC 2136 UPDATE bypass in DoH/DoQ/gRPC](https://junglewise.ai/threats/cve-2026-86003-coredns-rfc-2136-update-bypass-in-doh-doq-grpc)
- [CoreDNS unauthenticated memory exhaustion in DoH, DoQ, and DoH3](https://junglewise.ai/threats/cve-2026-82399-coredns-unauthenticated-memory-exhaustion-in-doh-doq-and-doh3)
- [CoreDNS panic in transfer plugin via k8s_external headless services](https://junglewise.ai/threats/cve-2026-62994-coredns-panic-in-transfer-plugin-via-k8s-external-headless)
- [CoreDNS NULL pointer dereference in proxyproto plugin](https://junglewise.ai/threats/cve-2026-62309-coredns-null-pointer-dereference-in-proxyproto-plugin)
- [CoreDNS NULL pointer dereference in rewrite plugin](https://junglewise.ai/threats/cve-2026-62299-coredns-null-pointer-dereference-in-rewrite-plugin)