Buffer Overflow in TOTOLINK CA300-PoE Device's QoS Rule Functionality
CVE-2026-123957

9.4CRITICAL

Key Information:

Vendor

Totolink
Status
Ca300-poe
Vendor
CVE Published:
7 November 2026

Badges

👾 Exploit Exists🟡 Public PoC

What is CVE-2026-123957?

A buffer overflow vulnerability exists in the TOTOLINK CA300-PoE, specifically within the setIpQosRules function in the /cgi-bin/cstecgi.cgi file. This vulnerability is triggered by manipulating the ipStart argument, which allows attackers to remotely exploit the device. The exploit has been made public, increasing the risk of malicious usage. Users are encouraged to apply available security patches to mitigate the risks associated with this vulnerability.

Affected Version(s)

CA300-PoE 6.2c.884

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-2026-123957 - Proof of Concept

References

https://vuldb.com/vuln/432020
vdb-entrytechnical-description
https://vuldb.com/vuln/432020/cti
signaturepermissions-required
https://vuldb.com/cve/CVE-2026-123957
third-party-advisory

CVSS V4

Score:
9.4
Severity:
CRITICAL
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

wxhwxhwxh_mie (VulDB User)
.