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ReviewHigh

CVE-2026-71942

DrayTek Corporation VigorSwitch G2540xs, VigorSwitch P2540xs, VigorSwitch FX2120

Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the mail_mailalert function. The vulnerability is caused by concatenating multiple smtpReceiver email addresses into a fixed-size buffer without checking the remaining buffer size. 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.

CVSS
8.6
EPSS
-
- percentile
CISA KEV
Not listed
Published
2026.08.25
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability-
Technical severityCVSS 8.6

Vulnerability overview

Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the mail_mailalert function. The vulnerability is caused by concatenating multiple smtpReceiver email addresses into a fixed-size buffer without checking the remaining buffer size. 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.

Affected product and versions

Product
DrayTek Corporation VigorSwitch G2540xs, VigorSwitch P2540xs, VigorSwitch FX2120
Affected versions
< 3.9.10, < 2.10.6, < 2.10.7, < 3.10.6, < 2.9.10
Fixed versions
No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that DrayTek Corporation VigorSwitch G2540xs, VigorSwitch P2540xs, VigorSwitch FX2120 and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CWE
CWE-120