Authenticated code execution via unbounded SSID formatting
Published Feb 21, 2026 · Updated Feb 21, 2026
Stack-based buffer overflow in Tenda A21 1.0.0.0 allows remote authenticated users to execute code through a crafted SSID. The form_fast_setting_wifi_set handler passes the unbounded ssid value to sprintf, which appends _5G into the 64-byte ssid_5g stack buffer. Low-privileged management access and the vulnerable Wi-Fi-unity branch are required; exploitation can run code as root or crash the HTTP service.
Summary
What happened
Stack-based buffer overflow in Tenda A21 1.0.0.0 allows remote authenticated users to execute code through a crafted SSID. The form_fast_setting_wifi_set handler passes the unbounded ssid value to sprintf, which appends _5G into the 64-byte ssid_5g stack buffer. Low-privileged management access and the vulnerable Wi-Fi-unity branch are required; exploitation can run code as root or crash the HTTP service.
The record
- CVE
- CVE-2026-2874
- Published
- Feb 21, 2026
- Updated
- Feb 21, 2026
- Vendor
- Shenzhen Tenda Technology Co., Ltd.
- Product
- A21
- Classifications
- CWE-121, CWE-119, T1190
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 21, 2026CVE publishedPublication date reported by the CVE source.
- Feb 21, 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=1.0.0.0
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
- Tenda A21 fast_setting_wifi_set oversized-SSID proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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