CVE-2026-62299
Description
A flaw was found in CoreDNS, a DNS server. A remote, unauthenticated client can exploit this vulnerability by sending a specially crafted DNS query that triggers a null pointer dereference in the rewrite plugin's EDNS0 response handling. This can lead to a denial of service (DoS) where the CoreDNS server either returns a SERVFAIL error, degrades availability, or crashes entirely, impacting the availability of DNS services.
Statement
This denial of service vulnerability affects CoreDNS instances in Red Hat OpenShift Container Platform and Red Hat Advanced Cluster Management for Kubernetes. A remote, unauthenticated attacker can send a specially crafted DNS query to trigger a panic in the CoreDNS rewrite plugin, leading to degraded service availability or a process crash. This occurs when the rewrite plugin is configured with specific edns0 rewrite rules that include the revert flag.
Mitigation
To mitigate this issue, ensure that the CoreDNS `rewrite` plugin is not configured with `edns0` rewrite rules that include the `revert` flag. If such configurations are present and not strictly necessary, remove or modify them to exclude the `revert` flag. This will prevent the vulnerable code path from being triggered by specially crafted DNS queries.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | N/A | 5.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | Low | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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