CVE-2026-42438: OpenClaw: Sender policy bypass in host media attachment reads allows unauthorized local file disclosure

Summary

OpenClaw's outbound host-media attachment read helper could enable host-local file reads based on global or agent-level read access without also honoring sender and group-scoped tool policy. In channel deployments that used toolsBySender or group policy to deny read for less-trusted senders, a denied sender could still trigger host-media attachment loading and cause readable local files to be returned through the outbound media path.

Affected Versions

This issue is known to affect OpenClaw 2026.4.9. Earlier versions were not confirmed during triage, so the advisory range is intentionally scoped to >= 2026.4.9 < 2026.4.10.

Impact

Affected deployments are those that both allow host read or filesystem root expansion at the global/agent level and rely on sender or group-scoped policy to deny read for some channel participants. In that configuration, the intended sender/group authorization boundary could be bypassed for outbound media reads, potentially disclosing host-local files readable by the OpenClaw process.

The issue does not require treating the model prompt as the security boundary. The vulnerable behavior was a concrete policy enforcement mismatch: sender/group policy denied read, while the host-media read helper could still be installed without that sender context.

Resolution

Fixed in OpenClaw 2026.4.10 by PR #64459, commit c949af9fabf3873b5b7c484090cb5f5ab6049a98. The fix threads sender, session, channel, and account context into outbound media access resolution and intersects host-media read capability creation with the existing group tool policy for read. When a concrete sender/group override denies read, OpenClaw no longer creates the host readFile media capability.

Additional attachment canonicalization hardening shipped in 2026.4.14, but the authorization bypass described here was fixed in 2026.4.10.

Credit

Thanks to @Telecaster2147 for reporting this issue.