CVE-2026-93858
Description
A flaw was found in OpenStack Mistral. The std.ssh_proxied built-in action accepts a user-supplied proxy_command parameter that is passed without validation to a system subprocess call on the Mistral executor host. An authenticated attacker can craft a malicious workflow that supplies an arbitrary command string as the proxy_command parameter, causing the Mistral executor to run that command as its operating system process user. Successful exploitation allows full remote code execution on the executor host with the privileges of the Mistral executor service account.
Statement
Red Hat product impact analysis pending. Component mapping required to determine which Red Hat OpenStack Platform or Red Hat OpenStack Services on OpenShift releases ship the affected Mistral version. Deployments that do not expose the std.ssh_proxied action (via the action_providers denylist configuration option in mistral.conf) are not exploitable via this vector.
Mitigation
Operators can disable the std.ssh_proxied action by adding 'std.ssh_proxied' to the denylist under the [action_providers] section of mistral.conf and restarting the Mistral executor service. Alternatively, restrict workflow execution privileges so that only trusted users or service accounts can create and run workflows containing std.ssh_proxied actions.
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 | 8.8 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | Low | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | High | N/A | N/A |
| Integrity Impact | High | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Red Hat CVSS v3 Score Explanation
S:U. Impact within Mistral executor security authority on control-plane nodes (commands as existing executor OS user). Base 8.8 per FIRST CVSS 3.1. See docs/SDLC/VM/mistral/psirtsupt-25043/CVE-2026-93858/references/cvss-analyst-decision-CVE-2026-93858.md (PSIRTSUPT-25043 verification).
Understanding the Weakness (CWE)
Confidentiality,Integrity,Availability,Non-Repudiation
Technical Impact: Execute Unauthorized Code or Commands; DoS: Crash, Exit, or Restart; Read Files or Directories; Modify Files or Directories; Read Application Data; Modify Application Data; Hide Activities
Attackers could execute unauthorized operating system commands, which could then be used to disable the product, or read and modify data for which the attacker does not have permissions to access directly. Since the targeted application is directly executing the commands instead of the attacker, any malicious activities may appear to come from the application or the application's owner.
Acknowledgements
Upstream acknowledges Chen YuXiang (Institute of Computing Technology, Chinese Academy of Sciences) as the original reporter.
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