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How the mentioned CVE works:
The vulnerability resides in OpenClaw versions before 2026.2.26, specifically within the system event handlers for member and message subtypes. These handlers fail to enforce sender authorization when processing events such as message_changed, message_deleted, and thread_broadcast. As a result, an attacker with basic privileges can enqueue unauthorized system events that originate from senders not present in Slack DM allowlists or per-channel user allowlists.
Normally, such events would be rejected if the sender is not explicitly allowed, but due to the missing validation, the event queue accepts them without checking the sender’s permissions. This allows a malicious actor to inject events that appear to come from trusted users, effectively bypassing the intended access controls.
The flaw can be triggered remotely over the network without any special prerequisites (low attack complexity, no authentication required beyond a valid low-privileged session). Once exploited, the attacker can manipulate message threads, delete or alter messages, and broadcast unauthorized updates across channels, undermining the integrity of the platform’s security model. The issue was identified by VulnCheck and assigned CVSS 4.0 base score 5.3 (Medium) with vector CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N.
Platform: OpenClaw
Version: <2026.2.26
Vulnerability : Authorization bypass
Severity: Medium
date: 2026-03-20
Prediction: 2026-02-26
Analytics under heading What Undercode Say:
Check installed OpenClaw version
openclaw --version
List current allowlists (DM and per-channel)
openclaw config get slack.allowlists
Simulate a malicious message_changed event (example payload)
curl -X POST https://your-openclaw-instance/api/events \
-H "Content-Type: application/json" \
-d '{
"type": "message_changed",
"sender": "untrusted_user",
"channel": "general",
"message": "spoofed content"
}'
Monitor event queue for unauthorized entries
tail -f /var/log/openclaw/events.log | grep "unauthorized"
Exploit:
An attacker with a low-privileged account sends a crafted message_changed, message_deleted, or `thread_broadcast` system event where the `sender` field is set to a non-allowlisted user. Because the event handler lacks sender authorization, the event is enqueued and processed, effectively bypassing Slack DM and per-channel allowlists. This allows the attacker to spoof actions from trusted users, alter message history, or inject broadcast updates without being explicitly authorized.
Protection from this CVE:
Upgrade to OpenClaw version 2026.2.26 or later. If immediate upgrade is not possible, apply the vendor-supplied patch that enforces sender authorization in all member and message subtype system event handlers. Additionally, review and tighten allowlist configurations, and monitor event logs for any unexpected event sources.
Impact:
Successful exploitation enables an attacker to bypass critical allowlist controls, leading to unauthorized message modifications, deletion of legitimate messages, and propagation of forged thread broadcasts. This compromises message integrity, disrupts communication workflows, and can be used to escalate privileges or perform social engineering attacks within the Slack-integrated environment.
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Sources:
Reported By: nvd.nist.gov
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