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high advisory

OpenClaw Sender Policy Bypass Vulnerability Leading to Local File Disclosure

OpenClaw versions prior to 2026.4.10 are vulnerable to a sender policy bypass, allowing attackers with restricted read access to disclose local files by triggering host-media attachment loading, bypassing authorization boundaries.

OpenClaw versions 2026.4.9 and earlier are susceptible to a sender policy bypass vulnerability (CVE-2026-42438) within the outbound host-media attachment read helper. This flaw enables attackers who have been denied read access through toolsBySender or group policies to circumvent sender and group-scoped authorization boundaries. By triggering the loading of host-media attachments, attackers can potentially retrieve readable local files via the outbound media path. Upgrading to version 2026.4.10 or later remediates this vulnerability, preventing unauthorized local file disclosure. The vulnerability impacts the confidentiality of data stored on systems running vulnerable versions of OpenClaw.

Attack Chain

  1. An attacker gains initial access to a system running a vulnerable version of OpenClaw, but is denied read access via configured toolsBySender or group policies.
  2. The attacker crafts a specific request that triggers the host-media attachment loading functionality within OpenClaw.
  3. This request leverages the vulnerable outbound host-media attachment read helper.
  4. The vulnerable helper bypasses configured sender and group-scoped authorization boundaries.
  5. The attacker specifies the path to a local file they would otherwise be unable to access directly due to access controls.
  6. OpenClaw processes the request, loading the specified file as part of the host-media attachment loading process.
  7. The file content is made accessible to the attacker through the outbound media path.
  8. The attacker retrieves the file content, achieving unauthorized local file disclosure.

Impact

Successful exploitation of this vulnerability (CVE-2026-42438) allows an attacker with limited privileges to read arbitrary local files on the affected system. This unauthorized access could lead to the disclosure of sensitive information, such as configuration files, user data, or other confidential documents. While the source does not specify the number of victims or sectors targeted, the potential impact is significant due to the possibility of widespread data breaches if the vulnerable OpenClaw versions are widely deployed.

Recommendation

  • Upgrade OpenClaw to version 2026.4.10 or later to remediate the sender policy bypass vulnerability described in CVE-2026-42438.
  • Monitor OpenClaw logs for unusual activity related to host-media attachment loading that may indicate exploitation attempts.
  • Implement the provided Sigma rule to detect suspicious process execution patterns indicative of potential exploitation attempts targeting CVE-2026-42438.

Detection coverage 2

Detect OpenClaw Local File Disclosure Attempt via Host-Media Attachment

high

Detects attempts to exploit CVE-2026-42438 by monitoring for suspicious activity related to host-media attachment loading in OpenClaw that could indicate a sender policy bypass and unauthorized local file disclosure.

sigma tactics: defense_evasion, privilege_escalation techniques: T1068 sources: process_creation, linux

Detect Suspicious Outbound Connections from OpenClaw After Attachment Load

medium

Detects suspicious outbound network connections originating from the OpenClaw process immediately after a host-media attachment is loaded, potentially indicating data exfiltration following a successful CVE-2026-42438 exploitation.

sigma tactics: command_and_control, exfiltration techniques: T1041 sources: network_connection, linux

Detection queries are kept inside the platform. Get full rules →