Quantum Secular Labs / Blog / Advisories

CVE-2026-121597: Executing a manipulation of the argument functionType can lead to stack-based buffer overflow.

CVE-2026-121597 is rated critical with a CVSS v3.1 base score of 9.9. Per its scoring, it can be exploited over the network, without any user interaction. The scored impact on confidentiality, integrity and availability is the highest available.

Vulnerability description

A weakness has been identified in TOTOLINK A950RG 4.1.2cu.5268_B20221104. This affects the function setAppEasyWizardConfig of the file /cgi-bin/cstecgi.cgi of the component Easy Setup Wizard Handler. Executing a manipulation of the argument functionType can lead to stack-based buffer overflow. The attack may be performed from remote. The exploit has been made available to the public and could be used for attacks.

Severity breakdown

CVSS v3.1 9.9: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

  • Attack vector: Network. Exploitable remotely over the network, with no need for local or physical access.
  • Attack complexity: Low. No special conditions; the attack can be repeated reliably.
  • Privileges required: Low. A basic user account is enough.
  • User interaction: None. No action from any user is needed.
  • Scope: Changed. Impact reaches beyond the vulnerable component to other resources.
  • Confidentiality impact: High. Total loss of confidentiality; sensitive data can be fully disclosed.
  • Integrity impact: High. Total loss of integrity; data or system state can be fully modified.
  • Availability impact: High. Total loss of availability; the component can be shut down.

Underlying weakness

CWE-119: Improper Restriction of Operations within the Bounds of a Memory Buffer

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.

CWE-121: Stack-based Buffer Overflow

The product writes past the end of a buffer that was allocated on the stack.

Affected products

    References