Vulnerability · Published Sep 8, 2026 · Assigned by VulnCheck
CVE-2026-82533DeepSeek Harness < 0.1.2-alpha.1 Authentication Bypass via Host Header Spoofing
Critical 9.6
In plain English
A critical-severity security flaw in DeepSeek Harness from DeepSeek. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 1.2% (higher than 69% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| npm | @deepseek-ai/dsh-client-connection | 0.1.2-alpha.1 | GHSA-8m2g-8cgm-3vcp |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| DeepSeek | DeepSeek Harness | 0 – before 0.1.2-alpha.1 |
Weakness: CWE-807 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H
References
- Researcher Blog technical-description, exploit
- Release Notes release-notes
- Patch Commit patch
- https://www.vulncheck.com/advisories/deepseek-harness-alpha-1-authentication-bypass-via-host-header-spoofing third-party-advisory