CVE-2026-82533: DeepSeek Harness < 0.1.2-alpha.1 Authentication Bypass via Host Header Spoofing
DeepSeek Harness before 0.1.2-alpha.1 contains an authentication bypass vulnerability in its local HTTP control-plane API that allows attackers to gain full agent control by supplying a spoofed Host header, as the server validates only the client-supplied Host header value rather than the actual TCP connection origin. Attackers can exploit this flaw to invoke privileged commands such as commands/execute with danger-full-access permissions, escalate session approval policies to unconfined execution, and retrieve all stored conversations without any credential or API key.
Affected Software
Event History
Frequently Asked Questions
Which deployments are exposed?
Deployments running DeepSeek Harness before 0.1.2-alpha.1 are affected if an attacker can send requests to the local HTTP control-plane API. The issue is in validation of the client-supplied Host header rather than the actual TCP connection origin.
Does exploitation require credentials or an API key?
No. An attacker can bypass authentication by supplying a spoofed Host header, without any credential or API key. User interaction is required according to the supplied severity vector.
What access can an attacker obtain after bypassing authentication?
An attacker can gain full agent control, including invoking privileged commands such as commands/execute with danger-full-access permissions. They can also escalate session approval policies to unconfined execution and retrieve all stored conversations.
How can I determine whether my installation is affected?
Check the installed DeepSeek Harness version. Versions before 0.1.2-alpha.1 are affected; 0.1.2-alpha.1 is the referenced release containing the fix.