CVE-2026-85621 in LobeChat
Summary
by MITRE • 09/04/2026
LobeChat (LobeHub) 2.2.1 does not properly verify inbound chat-platform webhook signatures in the QQ and Feishu adapters. The webhook route (/api/agent/webhooks/:platform) is unauthenticated by design and delegates verification to each adapter; the QQ adapter performs no Ed25519 signature verification on dispatched message events, and the Feishu adapter only performs an optional static-token comparison that is skipped when no token is configured (the default) and is not a body signature. An unauthenticated attacker who knows the public webhook URL can POST forged inbound messages with an attacker-chosen sender identity and arbitrary text, causing the bot owner's agent to process attacker-controlled input and treat the attacker as a trusted platform sender.
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Analysis
by VulDB Data Team • 09/04/2026
The vulnerability identified in LobeChat versions 2.2.1 involves critical authentication failures within its webhook integration architecture for QQ and Feishu platforms. The system design delegates signature verification responsibilities to individual adapter modules rather than enforcing centralized validation at the entry point of the /api/agent/webhooks/:platform route. This architectural choice introduces significant risk when adapters fail to implement robust cryptographic checks, as observed in this specific release where both major platform integrations exhibit severe deficiencies in input authentication mechanisms.
In the case of the QQ adapter, there is a complete absence of Ed25519 signature verification for dispatched message events. Webhook security standards typically require that incoming requests be cryptographically signed using private keys held exclusively by the service provider and verified against public keys or shared secrets on the receiving end to ensure integrity and authenticity. The lack of this verification means that any entity capable of reaching the webhook endpoint can inject messages without proving their origin, effectively bypassing all identity assurance controls intended for platform-specific communications.
The Feishu adapter presents a similar but distinct failure mode characterized by conditional authentication logic that defaults to no protection. While it attempts to perform static-token comparison, this mechanism is entirely optional and disabled when no token is configured, which represents the default state of the application. Furthermore, even if a token were provided, the implementation relies on simple string matching rather than verifying the integrity of the request body through cryptographic signatures. This approach fails to protect against message tampering or replay attacks and does not guarantee that the sender identity embedded in the payload has not been forged by an external actor.
An unauthenticated attacker who is aware of the public webhook URL can exploit these flaws to send POST requests containing fabricated inbound messages. By manipulating the JSON payloads, the attacker can specify arbitrary sender identities and inject malicious or deceptive text content into the chat stream. Because the system processes these inputs as if they originated from legitimate users on QQ or Feishu, the AI agent will treat the forged input with full trust, leading to unauthorized command execution, data exfiltration through prompt injection, or manipulation of the conversation context based on attacker-controlled parameters rather than genuine user intent.
This vulnerability aligns closely with CWE-287 Improper Authentication and CWE-345 Insufficient Verification of Data Authenticity under industry classification standards. From a tactical perspective, it maps to MITRE ATT&CK technique T1078 Valid Accounts as the attacker impersonates legitimate platform users, and potentially T1059 Command and Scripting Interpreter if the injected content triggers unintended agent behaviors or tool usage. The impact extends beyond simple spam, encompassing potential compromise of downstream systems accessed by the AI agent and erosion of trust in automated conversational interfaces.
Mitigation strategies must prioritize immediate remediation of webhook validation logic. Developers should enforce mandatory Ed25519 signature verification for QQ integrations using verified public keys provided by Tencent. For Feishu, organizations must configure a strong static token if relying on that method, though migrating to HMAC-based body signatures is strongly recommended to ensure payload integrity. Additionally, implementing rate limiting and IP allowlisting at the network perimeter can provide defense-in-depth against automated abuse of these endpoints until code-level fixes are deployed in subsequent releases.