CVE-2026-71939

DrayTek VigorSwitch Multiple Models Buffer Overflow via acl_general_setup Add ACE

Published Aug 24, 2026 CVSS 4.0 · 8.6 High EPSS < 1% KEV · Not listed
Description
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the acl_general_setup Add ACE function. The vulnerability is caused by copying the name field into a fixed-size buffer without length validation. A remote attacker can trigger this vulnerability via crafted input, causing a denial of service or potentially executing arbitrary commands. Exploitation requires valid administrative credentials for the device's web management interface.

Analysis

AI-generated

Technical impact

A buffer overflow exists in the acl_general_setup Add ACE routine of multiple DrayTek VigorSwitch models. The bug arises when the code copies an ACE name field into a fixed‑size buffer without validating its length. If an attacker crafts input for the web management interface while holding administrative credentials, the overflow can crash the device or, in the worst case, allow the execution of arbitrary commands on the switch stack. The vulnerability is classified as high severity with a CVSS score of 8.6.

Affected Systems

The issue affects a range of DrayTek VigorSwitch devices, including FX2120, G1280, G1282, G2100, G2121, G2280x, G2282x, G2540x, G2540xs, G2542x, P1280, P1281x, P1282, P2100, P2121, P2280x, P2282x, P2540x, P2540xs, P2542x, P2542xh, PQ2121x, PQ2200xb, PQ2300xb, PX2060, Q2121x, Q2200x, and Q2300x. Firmware information is not supplied, so all firmware builds for each model are potentially vulnerable.

Risk and Exploitability

The CVSS rating of 8.6 indicates a high severity vulnerability. Although the EPSS score is not available, exploitation requires authenticated access to the device’s web console, limiting the attack surface to users who have administrative privileges or attackers who have compromised the network. The vulnerability is not listed in CISA’s KEV catalog; however, its high severity and wide product coverage combine to keep the overall risk significant until the device is patched.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Apply the latest firmware update from DrayTek that includes the buffer overflow fix in the ACL add function.
  • Restrict administrative access to the web interface by placing the switch behind a secure, internal network segment and enforcing strong, regularly changed credentials.
  • If the ACL function is not required, disable it or monitor for unauthorized attempts to add ACE entries.

Generated by OpenCVE AI on August 24, 2026 at 19:37 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the acl_general_setup Add ACE function. The vulnerability is caused by copying the name field into a fixed-size buffer without length validation. A remote attacker can trigger this vulnerability via crafted input, causing a denial of service or potentially executing arbitrary commands. Exploitation requires valid administrative credentials for the device's web management interface.
Title DrayTek VigorSwitch Multiple Models Buffer Overflow via acl_general_setup Add ACE
First Time appeared Draytek
Draytek vigorswitch Fx2120 Firmware
Draytek vigorswitch G1282 Firmware
Draytek vigorswitch G2100 Firmware
Draytek vigorswitch G2121 Firmware
Draytek vigorswitch G2280x Firmware
Draytek vigorswitch G2540xs Firmware
Draytek vigorswitch P1282 Firmware
Draytek vigorswitch P2100 Firmware
Draytek vigorswitch P2280x Firmware
Draytek vigorswitch P2540xs Firmware
Draytek vigorswitch Pq2121x Firmware
Draytek vigorswitch Pq2200xb Firmware
Draytek vigorswitch Q2121x Firmware
Draytek vigorswitch Q2200x Firmware
Weaknesses CWE-120
CPEs cpe:2.3:o:draytek:vigorswitch_fx2120_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_g1282_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_g2100_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_g2121_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_g2280x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_g2540xs_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_p1282_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_p2100_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_p2280x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_p2540xs_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_pq2121x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_pq2200xb_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_q2121x_firmware:*:*:*:*:*:*:*:*
cpe:2.3:o:draytek:vigorswitch_q2200x_firmware:*:*:*:*:*:*:*:*
Vendors & Products Draytek
Draytek vigorswitch Fx2120 Firmware
Draytek vigorswitch G1282 Firmware
Draytek vigorswitch G2100 Firmware
Draytek vigorswitch G2121 Firmware
Draytek vigorswitch G2280x Firmware
Draytek vigorswitch G2540xs Firmware
Draytek vigorswitch P1282 Firmware
Draytek vigorswitch P2100 Firmware
Draytek vigorswitch P2280x Firmware
Draytek vigorswitch P2540xs Firmware
Draytek vigorswitch Pq2121x Firmware
Draytek vigorswitch Pq2200xb Firmware
Draytek vigorswitch Q2121x Firmware
Draytek vigorswitch Q2200x Firmware
References
Metrics cvssV3_1

{'score': 7.2, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H'}

cvssV4_0

{'score': 8.6, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N'}