# CVE-2026-71936: DrayTek VigorSwitch buffer overflow in sysreboot function

Source: https://junglewise.ai/threats/cve-2026-71936-draytek-vigorswitch-buffer-overflow-in-sysreboot-function  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-24. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-71936 · Severity: high · CVSS 7.2 · Published 2026-08-24

DrayTek VigorSwitch is a network switch used in enterprise environments for traffic management and network connectivity. A buffer overflow vulnerability in the sysreboot function can be exploited by an authenticated administrator to cause denial of service or execute arbitrary code on the device. An attacker with valid admin credentials could gain full control of the switch, potentially disrupting network operations or accessing sensitive traffic passing through the device.

Technologies: [DrayTek VigorSwitch FX2120](https://junglewise.ai/threats/technologies/vigorswitch-fx2120), [DrayTek VigorSwitch G1280](https://junglewise.ai/threats/technologies/vigorswitch-g1280), [DrayTek VigorSwitch G1282](https://junglewise.ai/threats/technologies/vigorswitch-g1282), [DrayTek VigorSwitch G2100](https://junglewise.ai/threats/technologies/vigorswitch-g2100), [DrayTek VigorSwitch G2121](https://junglewise.ai/threats/technologies/vigorswitch-g2121), [DrayTek VigorSwitch G2280x](https://junglewise.ai/threats/technologies/vigorswitch-g2280x), [DrayTek VigorSwitch G2282x](https://junglewise.ai/threats/technologies/vigorswitch-g2282x), [DrayTek VigorSwitch G2540x](https://junglewise.ai/threats/technologies/vigorswitch-g2540x), [DrayTek VigorSwitch G2540xs](https://junglewise.ai/threats/technologies/vigorswitch-g2540xs), [DrayTek VigorSwitch G2542x](https://junglewise.ai/threats/technologies/vigorswitch-g2542x), [DrayTek VigorSwitch P1280](https://junglewise.ai/threats/technologies/vigorswitch-p1280), [DrayTek VigorSwitch P1281x](https://junglewise.ai/threats/technologies/vigorswitch-p1281x), [DrayTek VigorSwitch P1282](https://junglewise.ai/threats/technologies/vigorswitch-p1282), [DrayTek VigorSwitch P2100](https://junglewise.ai/threats/technologies/vigorswitch-p2100), [DrayTek VigorSwitch P2121](https://junglewise.ai/threats/technologies/vigorswitch-p2121), [DrayTek VigorSwitch P2280x](https://junglewise.ai/threats/technologies/vigorswitch-p2280x), [DrayTek VigorSwitch P2282x](https://junglewise.ai/threats/technologies/vigorswitch-p2282x), [DrayTek VigorSwitch P2540x](https://junglewise.ai/threats/technologies/vigorswitch-p2540x), [DrayTek VigorSwitch P2540xs](https://junglewise.ai/threats/technologies/vigorswitch-p2540xs), [DrayTek VigorSwitch P2542x](https://junglewise.ai/threats/technologies/vigorswitch-p2542x), [DrayTek VigorSwitch P2542xh](https://junglewise.ai/threats/technologies/vigorswitch-p2542xh), [DrayTek VigorSwitch PQ2121x](https://junglewise.ai/threats/technologies/vigorswitch-pq2121x), [DrayTek VigorSwitch PQ2200xb](https://junglewise.ai/threats/technologies/vigorswitch-pq2200xb), [DrayTek VigorSwitch PQ2300xb](https://junglewise.ai/threats/technologies/vigorswitch-pq2300xb), [DrayTek VigorSwitch PX2060](https://junglewise.ai/threats/technologies/vigorswitch-px2060), [DrayTek VigorSwitch Q2121x](https://junglewise.ai/threats/technologies/vigorswitch-q2121x), [DrayTek VigorSwitch Q2200x](https://junglewise.ai/threats/technologies/vigorswitch-q2200x), [DrayTek VigorSwitch Q2300x](https://junglewise.ai/threats/technologies/vigorswitch-q2300x). Vendors: [DrayTek](https://junglewise.ai/threats/vendors/draytek).

## Quick answers

**Is CVE-2026-71936 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-71936 being exploited in the wild.

**How severe is CVE-2026-71936?** High severity, with a CVSS score of 7.2, published 24 August 2026.

**Which products and versions are affected?** DrayTek VigorSwitch FX2120 < 3.9.10; DrayTek VigorSwitch G1280 < 2.9.10; DrayTek VigorSwitch G1282 < 2.9.10; DrayTek VigorSwitch G2100 < 2.9.10; and 24 more.

**Is there a fix for CVE-2026-71936?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-71936 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-71936?** 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 buffer overflow (CWE-120) in the sysreboot function, caused by unsafe concatenation of split valueN parameters into a fixed-size buffer without proper bounds checking. The vulnerability is reachable only via the web management interface and requires valid administrative credentials to authenticate. Exploitation via crafted input can result in denial of service or arbitrary code execution on the affected appliance. Patches are available for all affected models, ranging from firmware version 2.9.10 to 3.10.6 depending on the specific VigorSwitch model.

## Affected products

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

## Timeline

- 2026-08-24: disclosed

## References

- [https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/](https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/)
- [https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-buffer-overflow-via-sysreboot](https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-buffer-overflow-via-sysreboot)

## Related threats

- [DrayTek VigorSwitch command injection in setDevNet](https://junglewise.ai/threats/cve-2026-71943-draytek-vigorswitch-command-injection-in-setdevnet)
- [DrayTek VigorSwitch buffer overflow in mail_mailalert](https://junglewise.ai/threats/cve-2026-71942-draytek-vigorswitch-buffer-overflow-in-mail-mailalert)
- [DrayTek VigorSwitch buffer overflow in diag_logmail](https://junglewise.ai/threats/cve-2026-71941-draytek-vigorswitch-buffer-overflow-in-diag-logmail)
- [DrayTek VigorSwitch buffer overflow in acl_general_setup Edit ACE](https://junglewise.ai/threats/cve-2026-71940-draytek-vigorswitch-buffer-overflow-in-acl-general-setup-edit-ace)
- [DrayTek VigorSwitch buffer overflow in acl_general_setup](https://junglewise.ai/threats/cve-2026-71939-draytek-vigorswitch-buffer-overflow-in-acl-general-setup)