CVE-2026-66798
Description
A flaw was found in cluster-backup-operator. A namespace administrator in open-cluster-management-backup can create a Restore Custom Resource (CR) with malicious hooks. These hooks allow the execution of arbitrary commands within any matching restored pod, leading to the exfiltration of ServiceAccount tokens. This bypasses normal access controls, granting the attacker unauthorized execution access to pods and their associated Service Accounts.
Statement
This vulnerability is rated as Important because an authenticated user with administrative access to the backup namespace can achieve cluster-wide privilege escalation. By defining custom restore operations containing uninspected execution hooks, an attacker circumvents standard pod execution controls across target restored workloads. This bypass enables unauthorized command execution and credential exfiltration across different namespaces, exceeding the boundary of the backup operator namespace.
Mitigation
To mitigate this issue, ensure that only highly trusted administrators are granted `namespace-admin` privileges within the `open-cluster-management-backup` namespace. This restricts the ability to create or modify `Restore` Custom Resources with malicious hooks, thereby preventing arbitrary command execution in restored pods.
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).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.8 | N/A | 4.3 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | Low | N/A | None |
| User Interaction | None | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | High | N/A | None |
| Integrity Impact | High | N/A | None |
| Availability Impact | High | N/A | Low |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:L/E:U/RL:O/RC:C
Red Hat CVSS v3 Score Explanation
S:U — hooks execute within pods the operator already manages. PR:L — namespace-admin in backup namespace.
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
If a malicious user injects a character (such as a semi-colon) that delimits the end of one command and the beginning of another, it may be possible to then insert an entirely new and unrelated command that was not intended to be executed. This gives an attacker a privilege or capability that they would not otherwise have.
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