Authenticated switch crash via unchecked email concatenation
Published Aug 24, 2026 · Updated Aug 24, 2026
Classic buffer overflow in DrayTek VigorSwitch firmware allows remote authenticated users to crash an affected switch via mail-alert input. The mail_mailalert function concatenates multiple smtpReceiver addresses into a fixed-size buffer without checking its remaining capacity. Administrative web-management credentials are required; command execution remains unproven because DrayTek reports no practical attack path.
Summary
What happened
Classic buffer overflow in DrayTek VigorSwitch firmware allows remote authenticated users to crash an affected switch via mail-alert input. The mail_mailalert function concatenates multiple smtpReceiver addresses into a fixed-size buffer without checking its remaining capacity. Administrative web-management credentials are required; command execution remains unproven because DrayTek reports no practical attack path.
The record
- CVE
- CVE-2026-71942
- Published
- Aug 24, 2026
- Updated
- Aug 24, 2026
- Vendor
- DrayTek
- Product
- VigorSwitch P2100
- Classifications
- CWE-120, T1190
- Attack vector
- network
- Privileges
- admin
Timeline
How it unfolded
- Aug 24, 2026CVE publishedPublication date reported by the CVE source.
- Aug 24, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <2.9.10
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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Technologies
Your stack
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Your stack
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