CVE-2026-71940: DrayTek VigorSwitch buffer overflow in acl_general_setup Edit ACE

CVE-2026-71940 · Severity: high · CVSS 7.2 · Published 2026-08-24

DrayTek VigorSwitch devices are network switches used in enterprise environments to manage and control data traffic. A buffer overflow vulnerability in the administrative configuration interface allows authenticated administrators with malicious intent to cause system crashes or execute arbitrary code on the device, potentially compromising network operations and data integrity.

Technologies: DrayTek VigorSwitch FX2120, DrayTek VigorSwitch G1280, DrayTek VigorSwitch G1282, DrayTek VigorSwitch G2100, DrayTek VigorSwitch G2121, DrayTek VigorSwitch G2280x, DrayTek VigorSwitch G2282x, DrayTek VigorSwitch G2540x, DrayTek VigorSwitch G2540xs, DrayTek VigorSwitch G2542x, DrayTek VigorSwitch P1280, DrayTek VigorSwitch P1281x, DrayTek VigorSwitch P1282, DrayTek VigorSwitch P2100, DrayTek VigorSwitch P2121, DrayTek VigorSwitch P2280x, DrayTek VigorSwitch P2282x, DrayTek VigorSwitch P2540x, DrayTek VigorSwitch P2540xs, DrayTek VigorSwitch P2542x, DrayTek VigorSwitch P2542xh, DrayTek VigorSwitch PQ2121x, DrayTek VigorSwitch PQ2200xb, DrayTek VigorSwitch PQ2300xb, DrayTek VigorSwitch PX2060, DrayTek VigorSwitch Q2121x, DrayTek VigorSwitch Q2200x, DrayTek VigorSwitch Q2300x. Vendors: DrayTek.

Quick answers

Is CVE-2026-71940 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-71940 being exploited in the wild.
How severe is CVE-2026-71940?
High severity, with a CVSS score of 7.2, published 24 August 2026.
Which products and versions are affected?
DrayTek VigorSwitch FX2120 before 3.9.10; DrayTek VigorSwitch G1280 before 2.9.10; DrayTek VigorSwitch G1282 before 2.9.10; DrayTek VigorSwitch G2100 before 2.9.10; and 24 more.
Is there a fix for CVE-2026-71940?
A patch was published on 2026-08-24: Firmware updates released for all affected models Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-71940 attacked?
It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-71940?
Check whether you run DrayTek VigorSwitch FX2120, DrayTek VigorSwitch G1280, DrayTek VigorSwitch G1282 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

The vulnerability is a classic stack-based buffer overflow (CWE-120) in the acl_general_setup Edit ACE function within the mainfunction.cgi component. The flaw occurs when user-supplied input from the name field is copied into a fixed-size buffer without proper length validation. An attacker with valid administrative credentials can send a crafted HTTP request to the web management interface containing an oversized name parameter, overflowing the buffer and potentially overwriting adjacent memory including the function return address. This enables denial of service through a crash or code execution with the privileges of the web management process. Patches are available from DrayTek with fixed firmware versions for all affected models.

Affected products

  • DrayTek VigorSwitch G2540xs before 3.9.10
  • DrayTek VigorSwitch P2540xs before 3.9.10
  • DrayTek VigorSwitch FX2120 before 3.9.10
  • DrayTek VigorSwitch G2282x before 2.10.6
  • DrayTek VigorSwitch P2282x before 2.10.6
  • DrayTek VigorSwitch Q2300x before 2.10.7
  • DrayTek VigorSwitch PQ2300xb before 2.10.7
  • DrayTek VigorSwitch G2542x before 3.10.6
  • DrayTek VigorSwitch P2542x before 3.10.6
  • DrayTek VigorSwitch P2542xh before 3.10.6
  • DrayTek VigorSwitch PX2060 before 2.9.10
  • DrayTek VigorSwitch G1280 before 2.9.10
  • DrayTek VigorSwitch P1280 before 2.9.10
  • DrayTek VigorSwitch P1281x before 2.9.10
  • DrayTek VigorSwitch G1282 before 2.9.10
  • DrayTek VigorSwitch P1282 before 2.9.10
  • DrayTek VigorSwitch G2121 before 2.9.10
  • DrayTek VigorSwitch P2121 before 2.9.10
  • DrayTek VigorSwitch PQ2121x before 2.9.10
  • DrayTek VigorSwitch Q2121x before 2.9.10
  • DrayTek VigorSwitch G2280x before 2.9.10
  • DrayTek VigorSwitch P2280x before 2.9.10
  • DrayTek VigorSwitch Q2200x before 2.9.10
  • DrayTek VigorSwitch PQ2200xb before 2.9.10
  • DrayTek VigorSwitch G2100 before 2.9.10
  • DrayTek VigorSwitch P2100 before 2.9.10
  • DrayTek VigorSwitch G2540x before 2.9.10
  • DrayTek VigorSwitch P2540x before 2.9.10

Timeline

  • 2026-08-24: disclosed
  • 2026-08-24: patched: Firmware updates released for all affected models

References

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