# CVE-2026-71942: DrayTek VigorSwitch buffer overflow in mail_mailalert

Source: https://junglewise.ai/threats/cve-2026-71942-draytek-vigorswitch-buffer-overflow-in-mail-mailalert  
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-2026-71942 · Severity: high · CVSS 7.2 · Published 2026-08-24

DrayTek VigorSwitch is a managed network switch used in corporate environments to route and manage data traffic. A buffer overflow in the mail alert functionality allows authenticated administrators to trigger a denial of service or potentially execute arbitrary code on the device by sending specially crafted email configuration input. While this requires valid admin credentials, successful exploitation could give attackers complete control over network infrastructure.

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-2026-71942 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-71942 being exploited in the wild.

**How severe is CVE-2026-71942?** 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-2026-71942?** A patch was published on 2026-08-24: Fixed firmware versions released for all affected models Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-71942 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-71942?** 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 mail_mailalert function of multiple VigorSwitch firmware versions. The flaw occurs when the device concatenates multiple SMTP receiver email addresses into a fixed-size buffer without validating the remaining buffer capacity. An authenticated remote attacker with administrative credentials can exploit this via the web management interface by providing oversized email address input, leading to stack corruption. This can result in denial of service or, with careful payload crafting, arbitrary code execution on the affected appliance. Patches have been released for all affected models as of August 2026.

## 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: Fixed firmware versions released for all affected models

## 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-mail-mailalert](https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-buffer-overflow-via-mail-mailalert)

## 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 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)
- [DrayTek VigorSwitch buffer overflow in switch_lan_gvrp](https://junglewise.ai/threats/cve-2026-71938-draytek-vigorswitch-buffer-overflow-in-switch-lan-gvrp)