CVE-2026-54449 json
LangBot: Authenticated RCE Via MCP Configuration
published 3mo ago modified 24d ago also EUVD-2026-63480 , GHSA-3pvh-63gf-j9mw , PYSEC-2026-3473
- cvss
- 8.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.7%
- EPSS 0.7% chance of exploitation in 30 days, percentile 54%
- public exploits
- 0
- none known
Summary
LangBot is a global IM bot platform designed for LLMs. In version 4.10.7 and earlier, any authenticated user can add or change an STDIO MCP server configuration without an adequate authorization boundary. In src/langbot/pkg/provider/tools/loaders/mcp.py, StdioServerParameters accepts the configured command and arguments and starts a server-side subprocess on the LangBot server. An attacker who can sign up or obtain an account can use the Extensions MCP configuration to execute arbitrary commands with the privileges of the LangBot service, enabling data disclosure, modification, and service disruption. No fixed version is available as of this review.
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Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 2mo ago
Exploit prediction
0.72% chance of exploitation in the next 30 days, higher than 54% of all scored CVEs (FIRST EPSS, 2026-11-11).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| GitHub | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
| OSV | 3.1 | 8.8 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | langbot | <=4.10.5 |
no fix listed |
Affected products
- langbot-app LangBot
Classification
- Weakness
-
- CWE-77 Improper Neutralization of Special Elements used in a Command
References
-
github.com
/langbot-app/LangBot/security/advisories/GHSA-3pvh-63gf-j9mw
web
- ox.security /blog/mcp-supply-chain-advisory-rce-vulnerabilities-across-the-ai-ecosystem
-
github.com
/langbot-app/LangBot
package
-
pypi.org
/project/langbot
package
-
github.com
/advisories/GHSA-3pvh-63gf-j9mw
advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-54449
advisory
Sources
- CVE List CVE-2026-54449
- GitHub Advisory GHSA-3pvh-63gf-j9mw
- NVD CVE-2026-54449
- OSV PYSEC-2026-3473
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.