CVE-2026-71920
DrayTek VigorSwitch Multiple Models NULL Pointer Dereference via formlogout
Description
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.
INFO
Published Date :
Aug. 24, 2026, 6:17 p.m.
Last Modified :
Aug. 24, 2026, 7:16 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-71920
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 3.1 | MEDIUM | [email protected] | ||||
| CVSS 3.1 | MEDIUM | MITRE-CVE | ||||
| CVSS 4.0 | MEDIUM | 83251b91-4cc7-4094-a5c7-464a1b83ea10 | ||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update the device firmware to the latest version.
- Apply vendor-supplied security patches.
- Ensure proper input validation for cookie handling.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-71920.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-71920 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-71920
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-71920 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-71920 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Aug. 24, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-71920', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-08-24T18:17:16.143303Z'} -
New CVE Received by [email protected]
Aug. 24, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2540xs', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2540xs', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch FX2120', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2282x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.10.6', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2282x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.10.6', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch Q2300x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.10.7', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch PQ2300xb', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.10.7', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2542x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.10.6', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2542x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.10.6', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2542xh', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '3.10.6', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch PX2060', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G1280', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P1280', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P1281x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G1282', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P1282', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2121', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2121', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch PQ2121x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch Q2121x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2280x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2280x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch Q2200x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch PQ2200xb', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2100', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2100', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch G2540x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}, {'vendor': 'DrayTek Corporation', 'product': 'VigorSwitch P2540x', 'versions': [{'status': 'affected', 'version': '0', 'lessThan': '2.9.10', 'versionType': 'custom'}], 'defaultStatus': 'unaffected'}] Added Description 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. Added CVSS V4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CVSS V3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-476 Added Reference https://www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/ Added Reference https://www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-null-pointer-dereference-via-formlogout