Arbitrary file write via unsanitized upload filename
Published Mar 11, 2026 · Updated Mar 11, 2026
Path traversal in OpenBMB XAgent 1.0.0 allows remote attackers to write arbitrary files through the ToolServer upload endpoint. ToolServerNode's upload_file handler passes the multipart filename directly to os.path.join() and opens the resulting path for writing without containment validation. The ToolServerManager exposes the route, an unauthenticated session cookie reaches it, and successful traversal writes attacker-chosen content with the container's root permissions.
Summary
What happened
Path traversal in OpenBMB XAgent 1.0.0 allows remote attackers to write arbitrary files through the ToolServer upload endpoint. ToolServerNode's upload_file handler passes the multipart filename directly to os.path.join() and opens the resulting path for writing without containment validation. The ToolServerManager exposes the route, an unauthenticated session cookie reaches it, and successful traversal writes attacker-chosen content with the container's root permissions.
The record
- CVE
- CVE-2026-3954
- Published
- Mar 11, 2026
- Updated
- Mar 11, 2026
- Vendor
- OpenBMB
- Product
- XAgent
- Classifications
- CWE-22, CAPEC-126, T1105
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 11, 2026CVE publishedPublication date reported by the CVE source.
- Mar 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=1.0.0
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- GitHub issue 420 multipart traversal proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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