CVE-2026-82533

Deferred Deferred - Pending Action

Authentication Bypass in DeepSeek Harness Local API

Publication date: 2026-09-08

Last updated on: 2026-09-10

Assigner: VulnCheck

Description

DeepSeek Harness before 0.1.2-alpha.1 contains an authentication bypass vulnerability that grants unauthenticated access to its local HTTP agent-control API by accepting a client-supplied loopback Host header in place of validating the actual TCP connection origin. On the default configuration, a confined tool-executed process can reach the loopback API without any port exposure and use it to escape its own OS sandbox, escalate to unconfined execution, and disable the approval prompt. When the port is externally reachable via tunnel, SSH forward, or reverse proxy, a remote attacker can exploit the same flaw to create sessions, execute arbitrary commands, and exfiltrate stored conversation transcripts without credentials.

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published

2026-09-08

Last Modified

2026-09-10

Generated

2026-09-29

AI Q&A

2026-09-09

EPSS Evaluated

2026-09-27

NVD

CVE-2026-82533

Affected Vendors & Products

Vendor	Product	Version / Range
deepseek	harness	to 0.1.2-alpha.1 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-807	The product uses a protection mechanism that relies on the existence or values of an input, but the input can be modified by an untrusted actor in a way that bypasses the protection mechanism.

Attack-Flow Graph

Executive Summary

DeepSeek Harness before version 0.1.2-alpha.1 has an authentication bypass flaw in its local HTTP control-plane API. Attackers can spoof the Host header to trick the server into validating the wrong value, allowing full control over the agent. This enables execution of privileged commands, session policy escalation, and unauthorized access to stored conversations without credentials.

Detection Guidance

Detecting this vulnerability requires monitoring for unauthorized access to the DeepSeek Harness HTTP control-plane API. Check for unexpected Host headers in HTTP requests, unusual command invocations via commands/execute, or unapproved session approval policy changes. Inspect logs for connections originating from unexpected sources despite valid Host headers.

Impact Analysis

An attacker could gain full control of the DeepSeek Harness agent, execute arbitrary commands with high privileges, bypass security policies, and access sensitive data like stored conversations. This could lead to data breaches, unauthorized system access, or further network compromise depending on the agent's permissions.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, violating GDPR's data protection principles and HIPAA's security requirements for protected health information. Organizations using affected versions may face compliance violations, legal penalties, and reputational damage due to potential data exposure.

Mitigation Strategies

Immediately upgrade DeepSeek Harness to version 0.1.2-alpha.1 or later. Disable or restrict access to the local HTTP control-plane API if not required. Implement network-level controls to validate Host headers against actual TCP connection origins. Review and revoke any unauthorized sessions or commands executed via this vulnerability.

Hi! I’m here to help you understand CVE-2026-82533. Ask me anything about the vulnerability, its impact, or mitigation strategies.

0/70