CVE-2025-68151

Multiple CoreDNS server implementations (gRPC, HTTPS, and HTTP/3) lack critical resource-limiting controls. An unauthenticated remote attacker can exhaust memory and degrade or crash the server by opening many concurrent connections, streams, or sending oversized request bodies. The issue is similar in nature to CVE-2025-47950 (QUIC DoS) but affects additional server types that do not enforce connection limits, stream limits, or message size constraints.

1. Missing connection and stream limits (gRPC / HTTPS / HTTP3)

The affected servers do not enforce reasonable upper bounds on concurrent connections or active streams. An attacker can:

• Open many parallel connections
• Rapidly issue requests without limit
• Consume memory until the CoreDNS process becomes unresponsive or is terminated by the OOM killer

Testing demonstrates that modest resource configurations (e.g., 256 MB RAM) can be exhausted quickly. Increasing concurrency parameters in the PoCs allows attackers to scale the impact.

2. Missing message-size validation in the gRPC server

The gRPC server accepts arbitrarily large protobuf messages (default limit ~4 MB per request) without validating against DNS protocol constraints (maximum 64 KB). Sending multiple concurrent oversized messages can quickly exhaust available memory.

This vulnerability mirrors earlier hardening work in PR https://github.com/coredns/coredns/pull/7490, which applied checks for upstream proxying but left server-side request validation unprotected.

Result:

In all cases, remote unauthenticated attackers can reliably trigger memory exhaustion and cause a denial of service.

The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.

Kodem intelligence

v1.14.0

1. What is CVE-2025-68151? CVE-2025-68151 is a medium-severity allocation of resources without limits or throttling vulnerability in github.com/coredns/coredns (go), affecting versions < 1.14.0. It is fixed in 1.14.0. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
2. Which versions of github.com/coredns/coredns are affected by CVE-2025-68151? github.com/coredns/coredns (go) versions < 1.14.0 is affected.
3. Is there a fix for CVE-2025-68151? Yes. CVE-2025-68151 is fixed in 1.14.0. Upgrade to this version or later.
4. Is CVE-2025-68151 exploitable, and should I be worried? Whether CVE-2025-68151 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2025-68151 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2025-68151? Upgrade github.com/coredns/coredns to 1.14.0 or later.