CVE-2026-71920
6.9
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Summary
Multiple DrayTek VigorSwitch models contain a null pointer dereference vulnerability in the formlogout function. The vulnerability is caused by missing checks for an empty or absent Cookie header before string handling. A remote attacker can trigger this vulnerability via a crafted request to crash the service and cause a denial of service. Exploitation requires valid administrative credentials for the device's web management interface.
Affected Software
| Vendor | Product | Version Range | Status |
|---|---|---|---|
| DrayTek Corporation | VigorSwitch G2540xs | 0 < 3.9.10 | affected |
| DrayTek Corporation | VigorSwitch P2540xs | 0 < 3.9.10 | affected |
| DrayTek Corporation | VigorSwitch FX2120 | 0 < 3.9.10 | affected |
| DrayTek Corporation | VigorSwitch G2282x | 0 < 2.10.6 | affected |
| DrayTek Corporation | VigorSwitch P2282x | 0 < 2.10.6 | affected |
| DrayTek Corporation | VigorSwitch Q2300x | 0 < 2.10.7 | affected |
| DrayTek Corporation | VigorSwitch PQ2300xb | 0 < 2.10.7 | affected |
| DrayTek Corporation | VigorSwitch G2542x | 0 < 3.10.6 | affected |
| DrayTek Corporation | VigorSwitch P2542x | 0 < 3.10.6 | affected |
| DrayTek Corporation | VigorSwitch P2542xh | 0 < 3.10.6 | affected |
| DrayTek Corporation | VigorSwitch PX2060 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G1280 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P1280 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P1281x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G1282 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P1282 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G2121 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P2121 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch PQ2121x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch Q2121x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G2280x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P2280x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch Q2200x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch PQ2200xb | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G2100 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P2100 | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch G2540x | 0 < 2.9.10 | affected |
| DrayTek Corporation | VigorSwitch P2540x | 0 < 2.9.10 | affected |
Weaknesses
- CWE-476: NULL Pointer Dereference
ADP Enrichment
CISA ADP Vulnrichment
- SSVC:
- Exploitation: none
- Automatable: no
- Technical Impact: partial
References
- https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/
- https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-null-pointer-dereference-via-formlogout
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