Authenticated file overwrite via deterministic upload paths
Published May 5, 2026 · Updated May 5, 2026
TOCTOU in Langchain-Chatchat 0.3.1.0 through 0.3.1.3 allows remote authenticated users to overwrite uploaded files. The files handler derives storage solely from purpose, date, and file.filename, then opens the resulting path in write-binary mode without collision protection or per-user isolation. An adjacent-network user who uploads the same purpose and filename on the same day can replace content before the vision LLM retrieves it from disk.
Summary
What happened
TOCTOU in Langchain-Chatchat 0.3.1.0 through 0.3.1.3 allows remote authenticated users to overwrite uploaded files. The files handler derives storage solely from purpose, date, and file.filename, then opens the resulting path in write-binary mode without collision protection or per-user isolation. An adjacent-network user who uploads the same purpose and filename on the same day can replace content before the vision LLM retrieves it from disk.
The record
- CVE
- CVE-2026-7846
- Published
- May 5, 2026
- Updated
- May 5, 2026
- Vendor
- Chatchat-Space
- Product
- Langchain-Chatchat
- Classifications
- CWE-362, CWE-367, T1565.001
- Attack vector
- adjacent
- Privileges
- authenticated
Timeline
How it unfolded
- May 5, 2026CVE publishedPublication date reported by the CVE source.
- May 5, 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=0.3.1.0
- Affected versionversion=0.3.1.1
- Affected versionversion=0.3.1.2
- Affected versionversion=0.3.1.3
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
- Silent File Overwrite proof of conceptproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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