Authenticated arbitrary file write via unsandboxed attachment paths
Published Jun 1, 2026 · Updated Jun 1, 2026
Arbitrary file write in j3k0 MCP Google Workspace Server allows remote authenticated users to overwrite local files via Gmail attachment tools. The saveToDisk and bulk-save handlers pass caller-supplied paths to fs.writeFileSync after path.resolve removes traversal markers, without enforcing a base directory. Exploitation requires access to invoke a Gmail attachment MCP tool, available attachment content, and a target path writable by the server process; successful use writes attacker-influenced bytes outside the intended directory.
Summary
What happened
Arbitrary file write in j3k0 MCP Google Workspace Server allows remote authenticated users to overwrite local files via Gmail attachment tools. The saveToDisk and bulk-save handlers pass caller-supplied paths to fs.writeFileSync after path.resolve removes traversal markers, without enforcing a base directory. Exploitation requires access to invoke a Gmail attachment MCP tool, available attachment content, and a target path writable by the server process; successful use writes attacker-influenced bytes outside the intended directory.
The record
- CVE
- CVE-2026-10277
- Published
- Jun 1, 2026
- Updated
- Jun 1, 2026
- Vendor
- j3k0
- Product
- MCP Google Workspace Server
- Classifications
- CWE-73, CWE-266, CWE-284, T1105
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 1, 2026CVE publishedPublication date reported by the CVE source.
- Jun 1, 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?
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- Affected versionversion=831790e7d5c2663325733d9f5579cc339a267c4c
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 #19 reproduction requestfunctional · demonstrated
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Technologies
Your stack
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Your stack
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