LangBot has a cross-directory file upload vulnerability, which could lead to system takeover
Priority HIGH 70CWE-23Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- Low
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Code execution
- Confidentiality · integrity · availability
- High · High · High
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-434.
Summary
LangBot is a global IM bot platform designed for LLMs. In versions 4.1.0 up to but not including 4.3.5, authorized attackers can exploit the /api/v1/files/documents interface to perform arbitrary file uploads. Since this interface does not strictly restrict the storage directory of files on the server, it is possible to upload dangerous files to specific system directories. This is fixed in version 4.3.5.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00419 36th percentileScored 2026-11-07
Fix Fixed LangBot (langbot-app): 4.3.5
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| langbot-app | LangBot | 4.1.0 to before 4.3.5 | 4.3.5 | Patch available | CNA |
- LangBot Vendorlangbot-app Affected 4.1.0 to before 4.3.5 Fixed in 4.3.5 Patch available CNA
Remediation
- Fix · CNA LangBot (langbot-app) Fixed in 4.3.5
Timeline
- 2026-10-02 Threatist record created from CVE-2025-59835
References
More langbot-app vulnerabilities
- TI-2026-61802 LangBot through 0.4.17 Unauthenticated Plugin Registration via WebSocket CVSS 4.0HIGH 8.8
- TI-2026-61576 LangBot before 4.10.11 Authentication Bypass via Weak Recovery Key CVSS 4.0CRITICAL 9.2
- TI-2026-39312 LangBot: Authenticated RCE Via MCP Configuration CVSS 3.1HIGH 8.8
- TI-2026-76465 Missing Lark/Feishu webhook authenticity check in LangBot CVSS 4.0HIGH 8.3
Sources
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences