CVE-2025-65221
Memory Safety in Tenda Ac21 Firmware 16.03.08.16
Raw vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:LSummary
CVE-2025-65221 is a medium-severity Stack-based Buffer Overflow (CWE-121) vulnerability in Tenda Ac21 Firmware. Its CVSS base score is 4.3 (Medium).
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 21th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SI-10 (Information Input Validation) and SI-2 (Flaw Remediation) — see the control section below for these in your framework.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2025-198261
Vulnerability Data
Tenda AC21 V16.03.08.16 is vulnerable to Buffer Overflow via the list parameter of /goform/setPptpUserList.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Buffer overflow in the web interface (/goform/setPptpUserList) of the Tenda AC21 router enables remote code execution on a public-facing network device, directly facilitating T1190: Exploit Public-Facing Application.
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
Mitigating Controls (NIST 800-53 r5) AI
Directly enforces validation of the 'list' parameter size and format on /goform/setPptpUserList to block oversized input that triggers the stack buffer overflow.
Requires timely application of vendor patches that remediate the buffer overflow in the setPptpUserList handler of firmware V16.03.08.16.
Restricts administrative accounts and sessions permitted to invoke the PPTP user-list configuration endpoint, reducing the attack surface for exploitation.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Secure-development practices directly prevent introduction of stack buffer overflows.
Vulnerability scanning can discover stack buffer overflows but does not prevent their introduction.
Patching eliminates known instances of the weakness after discovery.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Security testing (fuzzing, static analysis) detects stack overflows before release.
Secure SDLC mandates buffer-safety practices that directly prevent stack overflows.
Application security requirements can specify buffer-size and input-validation rules.
Secure architecture principles include memory-safety and least-privilege stack usage.
Secure coding standards explicitly forbid unsafe buffer handling that causes CWE-121.
Change-management gates can enforce security reviews that catch buffer issues.