CVE-2026-56837

HIGH CVSS 8.6 PoC Available
Published: 2026-10-23
Modified: 2026-10-23
Enriched via mock
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AI Threat Summary

CVE-2026-56837 is a high-severity vulnerability with a CVSS score of 8.6 affecting the target software. Authentication can be bypassed allowing unauthenticated access. Threat hunters should monitor for exploit attempts and apply vendor patches immediately.

Description

PraisonAI is a multi-agent teams system. From version 4.6.56 to before version 4.6.59, PraisonAI's LinearBot starts a public webhook listener on 0.0.0.0 and treats LINEAR_WEBHOOK_SECRET as optional. When the secret is absent, startup only logs a warning and _handle_webhook() skips Linear-Signature verification entirely. An unauthenticated network caller who can reach the webhook endpoint can submit a forged Linear-Event: AgentSession request. The forged request is parsed, scheduled for background processing, dispatched to _handle_agent_session(), and passed into BotSessionManager.chat(). The bot then attempts to post the agent response back to Linear under the configured bot token. The PoV is offline and deterministic. It does not contact Linear. It calls the webhook handler directly, monkey-patches the outbound Linear comment path, and proves both sides of the boundary. This issue has been patched in version 4.6.59.

Attack Chain
1
Reconnaissance

Attacker identifies authentication endpoint and tests for bypass conditions

2
Initial Access

Attacker exploits CVE-2026-56837 authentication flaw to gain unauthorized access without valid credentials

3
Discovery

Attacker enumerates accessible resources, users, and configurations

4
Collection

Attacker exfiltrates sensitive data accessible without proper authorization

MITRE ATT&CK Techniques
T1078 Valid Accounts
Initial Access

Authentication bypass grants attacker access as legitimate user

T1548 Abuse Elevation Control Mechanism
Privilege Escalation

Bypassed auth may grant elevated or admin-level permissions

Indicators of Compromise
Type Value Description
user_agent Mozilla/5.0 (compatible; exploit/1.0) Generic exploit scanner user agent pattern
url /api/vuln-endpoint?payload=<malicious> Exploit attempt against application endpoint — monitor access logs for anomalous params
Remediation
1. Apply vendor-supplied security patches immediately. 2. If patches are unavailable, apply recommended mitigations from the vendor advisory. 3. Enable WAF rules or IDS signatures to detect exploitation attempts. 4. Monitor logs for indicators of compromise listed above. 5. Implement network segmentation to limit blast radius if exploitation occurs. 6. Subscribe to vendor security advisories for this product.
Quick Facts
CVE ID CVE-2026-56837
CVSS Score 8.6
Vector CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:H/A:L
Published 2026-10-23
Exploited No
CISA KEV No
PoC Available
References
External Resources
NVD Entry BleepingComputer The Hacker News