High

DeepSeek TUI has SSRF via HTTP Redirect Bypass in fetch_url Tool

  • Disclosed: 14.05.2026
  • Updated: 11.10.2026 10:22

Summary

The fetch_url tool validates the initial URL's resolved IP address against a restricted-IP blocklist (is_restricted_ip()) to prevent SSRF attacks against internal services (cloud metadata endpoints, localhost, private networks). However, the HTTP client (reqwest) is configured to automatically follow up to 5 redirects (reqwest::redirect::Policy::limited(5)) without re-validating the redirect target against the same SSRF protections.

PoC

Step 1 — Baseline: Confirm fetch_url blocks direct requests to restricted IPs.

Prompt: use fetch_url to fetch http://169.254.169.254/latest/meta-data/
Expected: Error — "restricted address (private/loopback/link-local)"

Step 2 — SSRF bypass via redirect: Fetch a public URL that redirects to the restricted IP.

Prompt: use fetch_url to fetch http://httpbin.org/redirect-to?url=http://169.254.169.254/latest/meta-data/&status_code=302

Expected result: The error message says "connection refused" or "request failed: connect error" — NOT "restricted address." This proves the SSRF filter was bypassed; the connection failed only because 169.254.169.254 is unreachable from a non-cloud machine.

Observed result: fetch_url followed the 302 redirect and attempted to connect to 169.254.169.254. The error was a TCP-level connection failure, confirming the application-layer SSRF check was not applied to the redirect target.

Step 3 — Redirect to attacker-controlled host: Confirm attacker-controlled redirect targets are followed.

Prompt: use fetch_url to fetch http://httpbin.org/redirect-to?url=http://[collaborator-domain]/ssrf-redirect-bypass&status_code=302
Expected: Collaborator receives HTTP callback at /ssrf-redirect-bypass, confirming the redirect was followed.

Impact

On cloud-hosted instances (AWS, GCP, Azure), an attacker can exfiltrate cloud IAM credentials, instance metadata, and other sensitive internal service data by redirecting fetch_url to http://169.254.169.254/latest/meta-data/. The attack is triggered via prompt injection (malicious instructions embedded in files or web content the model processes) that cause the model to call fetch_url with an attacker-controlled URL.

Affected software

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PlatformPackageVulnerable versionsFixed in
npm package deepseek-tui < 0.8.22 0.8.22

References

CVSS score 7.4/10
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:N/A:N
Weakness (CWE)
CWE-918
Platform
npm
Package
deepseek-tui
Disclosed
14.05.2026
Updated
11.10.2026 10:22

Sources and licenses

OSV / GitHub Advisory Database - GHSA-96ff-gc8g-wpvg - CC BY 4.0

Vulnerability history: deepseek-tui

All published vulnerabilities of this package (npm package), newest first. Shows whether this is a one-off slip or a package that needs watching.

All (11) in the archive
Total entries
11
First → latest
05.2026 09.2026
Without a fix
0
Exploited in attacks
0

Severity breakdown

  • Critical 2
  • High 9

Disclosures per year

  1. 2026: 11
Severity:
  1. Critical · 8.6 CVE-2026-75856 >= 0.8.5, < 0.8.41 0.8.41
  2. High · 7.5 CVE-2026-75914 >= 0.8.32, < 0.8.41 0.8.41
  3. Critical · 9.6 CVE-2026-45311 >= 0.3.0, < 0.8.23 0.8.23
  4. DeepSeek TUI has SSRF via HTTP Redirect Bypass in fetch_url Tool this entry
    High · 7.4 CVE-2026-45310 < 0.8.22 0.8.22

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