Stack-Based Buffer Overflow Vulnerability in Tenda AC21 Router
CVE-2026-1637

8.7HIGH

Key Information:

Vendor

Tenda
Status
Ac21
Vendor
CVE Published:
29 January 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-1637?

A stack-based buffer overflow vulnerability affects the Tenda AC21 router, specifically within the fromAdvSetMacMtuWan function located in the /goform/AdvSetMacMtuWan file. This flaw enables an attacker to potentially execute arbitrary code remotely. Given that exploits for this vulnerability are publicly available, it poses a significant security concern for users of the Tenda AC21 router version 16.03.08.16.

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Affected Version(s)

AC21 16.03.08.16

Exploit Proof of Concept (PoC)

PoC code is written by security researchers to demonstrate the vulnerability can be exploited. PoC code is also a key component for weaponization which could lead to ransomware.

CVE-2026-1637 - Proof of Concept

References

https://vuldb.com/?id.343416
vdb-entrytechnical-description
https://vuldb.com/?ctiid.343416
signaturepermissions-required
https://vuldb.com/?submit.740865
third-party-advisory

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • 🟡

    Public PoC available

  • 👾

    Exploit known to exist

  • Vulnerability published

  • Vulnerability Reserved

Credit

LX-LX (VulDB User)
JSON
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