Root code execution via unbounded password copy
Published Mar 16, 2026 · Updated Mar 16, 2026
Stack-based buffer overflow in Tenda AC8 16.03.50.11 and earlier allows attackers to execute code as root over the local network. The fromSysToolChangePwd handler copies the stored sys.userpass value through GetValue into a 36-byte stack buffer without bounding the copy to the destination. Factory-reset devices need no credentials; configured devices require the current administrator password to store the crafted value, and successful exploitation starts a root telnet service while crashing the HTTP server.
Summary
What happened
Stack-based buffer overflow in Tenda AC8 16.03.50.11 and earlier allows attackers to execute code as root over the local network. The fromSysToolChangePwd handler copies the stored sys.userpass value through GetValue into a 36-byte stack buffer without bounding the copy to the destination. Factory-reset devices need no credentials; configured devices require the current administrator password to store the crafted value, and successful exploitation starts a root telnet service while crashing the HTTP server.
The record
- CVE
- CVE-2026-4254
- Published
- Mar 16, 2026
- Updated
- Mar 16, 2026
- Vendor
- Shenzhen Tenda Technology Co., Ltd.
- Product
- AC8
- Classifications
- CWE-787, CWE-121, CWE-119, T1190
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Mar 16, 2026CVE publishedPublication date reported by the CVE source.
- Mar 16, 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=16.03.50.0
- Affected versionversion=16.03.50.1
- Affected versionversion=16.03.50.10
- Affected versionversion=16.03.50.11
- Affected versionversion=16.03.50.2
- Affected versionversion=16.03.50.3
- Affected versionversion=16.03.50.4
- Affected versionversion=16.03.50.5
- Affected versionversion=16.03.50.6
- Affected versionversion=16.03.50.7
- Affected versionversion=16.03.50.8
- Affected versionversion=16.03.50.9
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
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
- poc_SysToolChangePwd_BOF.pyfunctional · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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