CVE-2026-71935: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in DrayTek Corporation VigorSwitch G2540xs
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the webBackupAction function. The vulnerability is caused by repeated string concatenation of the pathN, valueN, key, and option fields into fixed-size stack buffers without total length checks. 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.
AI Analysis
Technical Summary
CVE-2026-71935 is a classic buffer overflow vulnerability in multiple DrayTek VigorSwitch models, specifically in the webBackupAction function. The flaw arises from repeated concatenation of input fields (pathN, valueN, key, option) into fixed-size stack buffers without verifying the total length, allowing a remote attacker with administrative access to trigger a buffer overflow. This can result in denial of service or potentially arbitrary code execution on the device.
Potential Impact
An attacker with valid administrative credentials to the device's web management interface can exploit this vulnerability to cause a denial of service or execute arbitrary commands, potentially compromising the device's integrity and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict administrative access to trusted users and networks to reduce the risk of exploitation.
CVE-2026-71935: Buffer Copy without Checking Size of Input ('Classic Buffer Overflow') in DrayTek Corporation VigorSwitch G2540xs
Description
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the webBackupAction function. The vulnerability is caused by repeated string concatenation of the pathN, valueN, key, and option fields into fixed-size stack buffers without total length checks. 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 v4.0
Score 8.6high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-71935 is a classic buffer overflow vulnerability in multiple DrayTek VigorSwitch models, specifically in the webBackupAction function. The flaw arises from repeated concatenation of input fields (pathN, valueN, key, option) into fixed-size stack buffers without verifying the total length, allowing a remote attacker with administrative access to trigger a buffer overflow. This can result in denial of service or potentially arbitrary code execution on the device.
Potential Impact
An attacker with valid administrative credentials to the device's web management interface can exploit this vulnerability to cause a denial of service or execute arbitrary commands, potentially compromising the device's integrity and availability.
Mitigation Recommendations
Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Until a fix is available, restrict administrative access to trusted users and networks to reduce the risk of exploitation.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- VulnCheck
- Date Reserved
- 2026-08-08T16:37:44.519Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a8c7defacd9273b49e1b466
Added to database: 08/24/2026, 17:22:55 UTC
Last enriched: 08/24/2026, 17:37:50 UTC
Last updated: 08/24/2026, 20:21:19 UTC
Views: 4
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