CVE-2026-71942
HIGHCVE-2026-71942 is a high-severity (CVSS 7.2) CWE-120 vulnerability. O3 Security confirms whether CVE-2026-71942 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the mail_mailalert function. The vulnerability is caused by concatenating multiple smtpReceiver email…
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-71942.
Description
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.
Detection & mitigation playbook
VulnerabilityDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for the affected component. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Remediation status
No patched version of the affected component has shipped for CVE-2026-71942 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
Mitigate without a patch
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-71942 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-71942. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-71942 in your dependencies?
O3 detects CVE-2026-71942 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.