CVE-2026-71935

DrayTek VigorSwitch Multiple Models Buffer Overflow via webBackupAction

HIGH

7.2

CVSS Score

Published: August 24, 2026 at 05:08 PM UTC

Updated: October 12, 2026 at 10:10 PM UTC

42 products affected across 1 vendorVigorswitch Q2200X FirmwareVigorswitch PQ2121X FirmwareVigorswitch PQ2200XB Firmware

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Severity

HIGH7.2

Exploit prediction

EPSS 0.7%

SSVC

No known exploit

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.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Vigorswitch FX2120 Firmware · Draytek

95%

v < 3.9.10

Affected range stops below 3.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch G1282 Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch G2100 Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch G2121 Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch G2280X Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch G2540XS Firmware · Draytek

95%

v < 3.9.10

Affected range stops below 3.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch P1282 Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch P2100 Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch P2280X Firmware · Draytek

95%

v < 2.9.10

Affected range stops below 2.9.10, so it looks safe — our inference, not a vendor statement

Vigorswitch P2540XS Firmware · Draytek

95%

v < 3.9.10

Affected range stops below 3.9.10, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/

References (2)

Vendor Advisory

Source: cverecord

https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/

Third Party Advisory

Source: cverecord

https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-buffer-overflow-via-webbackupaction

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.2HIGHVulnCheck

Attack Vector: NETWORK
Complexity: LOW
Privileges: HIGH
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusDEFERRED

CWE

CWE-120

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