Local code execution via TFTP argument overflow
Published Dec 8, 2021 · Updated Oct 16, 2025
Stack-based buffer overflow in the TFTP client library in FortiOS and affected Fortinet appliances allows local users to execute code. Fortinet has not disclosed the affected function or the exact operation that fails to bound crafted command-line arguments. Administrative CLI access is required; successful exploitation executes attacker-controlled code in the appliance context.
Summary
What happened
Stack-based buffer overflow in the TFTP client library in FortiOS and affected Fortinet appliances allows local users to execute code. Fortinet has not disclosed the affected function or the exact operation that fails to bound crafted command-line arguments. Administrative CLI access is required; successful exploitation executes attacker-controlled code in the appliance context.
The record
- CVE
- CVE-2021-42757
- Published
- Dec 8, 2021
- Updated
- Oct 16, 2025
- Vendor
- Fortinet
- Product
- FortiManager
- Classifications
- CWE-787, CWE-121
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- Dec 8, 2021CVE publishedPublication date reported by the CVE source.
- Oct 16, 2025Record 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=6.0.0 <=6.0.12
- Affected versionversion=6.2.0 <=6.2.13
- Affected versionversion=6.4.0 <=6.4.7
- Affected versionversion=7.0.0 <=7.0.2
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.
Public exploit references
No public exploit references are available in this record.
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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