Disclosed vulnerability
Hidden chrome.perplexity.mcp.addStdioServer API in Comet let extensions run arbitrary local commands
AIR-2025-0176 AIR record · 2025-11-perplexity-comet-mcp-stdio-api
From the supporting source
If the industry doesn't establish boundaries now, we're setting a precedent where AI browsers can bypass decades of security principleshelpnetsecurity.com
The record
Disclosed
2025-11-19
Vendor
Perplexity
Product
Perplexity Comet
Risk domain
Access control and permissions › Privilege escalation
Also touches
Data exfiltration channels
System type
Generative model
Who acted
AI was the target (contested) — a privileged private browser API reachable from any web origin
Attack surface
Browser agent
Autonomy level
Semi-autonomous
Initial vector
Privileged private browser api reachable from web origin
Impact type
Remote code execution, Malware delivery, Data exfiltration
Confidence
Medium
Submitted by
EAI Internal
Crosswalk
- OWASP Agentic Top 10 (2026)
- ASI03 – Identity and Privilege Abuse
- MITRE ATLAS
- AML.T0055 – Unsecured Credentials
- NIST AI RMF
- GOVERN 6.1
- EU AI Act
- Article 13
- ISO/IEC
- TR 24028; 42001; 23894
- AIUC-1
- B. Security
- Scope
- tool misuse
- Mitigation
- Apply least-privilege principle; Regular policy audits.
- Taxonomy
- Enkrypt AI agent risk taxonomy · Black-Box Red Teaming of Agentic AI: A Taxonomy-Driven Framework for Automated Risk Discovery
Blast radius
Comet installs before the 2025-11-20 silent update
Capability abused
Defense & remediation
Recorded defense
browser extension sandbox (bypassed by the vendor's own private API)
Guardrail kinds
Sandbox isolation
Guardrail outcome
Silent
Fix shipped
Perplexity silently disabled the MCP API on 2025-11-20 'out of an abundance of caution'
Taxonomy & references
Curator notes
SquareX research; Help Net Security's coverage is used as the source in place of the researchers' own writeup at labs.sqrx.com (permitted fallback). Chain per SquareX: reach the perplexity.ai origin (XSS or MitM) or stomp the trusted Comet Analytics extension ID, then call the private API to register an arbitrary stdio MCP server = arbitrary local command execution; ransomware PoC shown. DISPUTED: Perplexity called the claims 'entirely false', saying the API needs developer mode, sideloading and user consent. Disclosed to Perplexity 2025-11-04.
Supporting sources
Cite as
Enkrypt AI. "Hidden chrome.perplexity.mcp.addStdioServer API in Comet let extensions run arbitrary local commands". AIR, AIR-2025-0176. https://agentincident.vercel.app/i/AIR-2025-0176/ (accessed 2026-10-19).