DrayTek VigorSwitch Multiple Models Buffer Overflow via switch_lan_gvrp
Multiple DrayTek VigorSwitch models contain a buffer overflow vulnerability in the switch_lan_gvrp function. The vulnerability is caused by unsafe copying of the portList field into an undersized buffer. 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.
- Published
- Aug 24, 2026
- Updated
- Aug 26, 2026
- EPSS
- 0.7% · 51th percentile
- CWE
- CWE-120
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Report tools
Action score
34
Monitor
Low priority for now.
- CVSS
- 34 / 40 · 8.6 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.7%
CISA SSVC decision
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · VulnCheck
- 8.6
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Noroxi analysis
No Noroxi analysis for this record yet
We don't hand-write analysis for the hundreds of thousands of vulnerabilities in the database; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.
We use this product, ask for helpAffected systems
—
Versions reported by the vendor
Affected version ranges reported by the assigning authority (VulnCheck). Independent of NVD's CPE analysis and usually ahead of it.
DrayTek Corporation VigorSwitch FX2120
- before 3.9.10affected
DrayTek Corporation VigorSwitch G1280
- before 2.9.10affected
DrayTek Corporation VigorSwitch G1282
- before 2.9.10affected
DrayTek Corporation VigorSwitch G2100
- before 2.9.10affected
DrayTek Corporation VigorSwitch G2121
- before 2.9.10affected
DrayTek Corporation VigorSwitch G2280x
- before 2.9.10affected
DrayTek Corporation VigorSwitch G2282x
- before 2.10.6affected
DrayTek Corporation VigorSwitch G2540x
- before 2.9.10affected
DrayTek Corporation VigorSwitch G2540xs
- before 3.9.10affected
DrayTek Corporation VigorSwitch G2542x
- before 3.10.6affected
DrayTek Corporation VigorSwitch P1280
- before 2.9.10affected
DrayTek Corporation VigorSwitch P1281x
- before 2.9.10affected
Same product
draytek corporation: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-71921DrayTek VigorSwitch Multiple Models Pre-Authentication OS Command Injection via setget.cgi38Monitor
- CVE-2026-71943DrayTek VigorSwitch Multiple Models OS Command Injection via setDevNet35Monitor
- CVE-2026-71933DrayTek VigorSwitch Multiple Models Missing Authorization in Syslog Functions35Monitor
- CVE-2026-71931DrayTek VigorSwitch Multiple Models OS Command Injection via tftp_upgrade35Monitor
- CVE-2026-71930DrayTek VigorSwitch Multiple Models OS Command Injection via setTime35Monitor
- CVE-2026-71929DrayTek VigorSwitch Multiple Models OS Command Injection via setDevProto35Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
No fix version is recorded for this entry. Check the references for vendor advisories.
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Xiapu Luo (The Hong Kong Polytechnic University)finder
- Jincheng Wang (@winmt)Nanjing University of Posts and Telecommunicationsfinder
- Le Yu (Nanjing UniversityPosts and Telecommunications)finder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-719340 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via pingtrace34Monitor
- CVE-2026-719350 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via webBackupAction34Monitor
- CVE-2026-719360 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via sysreboot34Monitor
- CVE-2026-719370 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via poe_schedule_profile34Monitor
- CVE-2026-719390 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via acl_general_setup Add ACE34Monitor
- CVE-2026-719400 days apartDrayTek VigorSwitch Multiple Models Buffer Overflow via acl_general_setup Edit ACE34Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
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Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- Administrator privileges are required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- High
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')CVSS vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/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
nvd-secondary
Root cause
When data is copied, the source length is not compared with the size of the destination buffer. Excess data overwrites adjacent memory.
The bug in code
The whole CWE-120 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
char buf[256];memcpy(buf, pkt->data, pkt->len);Fixed
char buf[256];if (pkt->len > sizeof(buf)) { return -EINVAL;}memcpy(buf, pkt->data, pkt->len);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Buffer Overflow via Environment VariablesCAPEC-10likelihood: High · High
- Overflow BuffersCAPEC-100likelihood: High · Very High
- Client-side Injection-induced Buffer OverflowCAPEC-14likelihood: Medium · High
- Filter Failure through Buffer OverflowCAPEC-24likelihood: High · High
- MIME ConversionCAPEC-42likelihood: High · High
- Overflow Binary Resource FileCAPEC-44likelihood: High · Very High
- Buffer Overflow via Symbolic LinksCAPEC-45likelihood: High · High
- Overflow Variables and TagsCAPEC-46likelihood: High · High
ATT&CK techniques
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Change log
No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.
References
- www.draytek.com/about/security-advisory/multiple-vulnerabilities-in-vigorswitch-series-august-2026/
- www.vulncheck.com/advisories/draytek-vigorswitch-multiple-models-buffer-overflow-via-switch-lan-gvrp
Vendor advisories and official records. Exploit/PoC links are deliberately left out.