CVE-2026-42020: Stack-Based Buffer Overflow Flaw in Totolink Scores 9.1 on CVSS
A newly published critical vulnerability in Totolink carries a CVSS score of 9.1. Here is what is affected and how to respond.
Key points
- CVE-2026-42020 affects Totolink.
- CVSS 9.1 (Critical).
- No exploitation confirmed yet.
Totolink is affected by CVE-2026-42020, a stack-based buffer overflow that the National Vulnerability Database rates 9.1 out of 10.
At a glance
- CVE
- CVE-2026-42020
- Product
- Totolink
- CVSS
- 9.1 Critical
- Weakness
- stack-based buffer overflow
- Exploited
- No known exploitation
What is the vulnerability?
The NVD entry states: Multiple stack-based buffer overflow vulnerabilities exist in the boa formIpv6Setup pppoe functionality of Totolink X2000R TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. A specially crafted HTTP request can lead to arbitrary code execution. An attacker can make an authenticated HTTP request to trigger these vulnerabilities. This vulnerability concerns the pppoe_dns2 parameter.
Affected versions
| Vendor | Product | Versions |
|---|---|---|
| Totolink | Totolink | TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 |
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H.
Is it being exploited?
There is no public confirmation of exploitation at the time of publication. It does not appear in CISA's Known Exploited Vulnerabilities catalog. We will update this report if that changes.
What should you do?
- Identify whether the affected product and versions run in your environment.
- Apply the vendor update listed in the advisory as soon as it is available.
- Limit network exposure of the affected service until it is patched.
- Monitor the vendor advisory for updated guidance or exploitation reports.
What to do and how to stay safe: CVE-2026-42020
- Vulnerability severity scores ignore your specific architecture and context.
- Exploitability depends on network exposure and user behavior, not just code flaws.
- Prioritization requires continuous asset inventory and threat intelligence alignment.
Risk-based vulnerability management focuses your limited resources on the flaws that actually threaten your business. Start by mapping your critical assets and checking for active exploits to prioritize your backlog.
Step-by-step guide: Risk-Based Vulnerability Management: Prioritize Fixes by Actual Danger
General security guidance from the Threat Times newsroom. It is not confirmed advice from the organisations named in this story.
Frequently asked questions
What is CVE-2026-42020?
CVE-2026-42020 is a stack-based buffer overflow vulnerability in Totolink.
How severe is CVE-2026-42020?
It has a CVSS score of 9.1 Critical.
Is CVE-2026-42020 being exploited?
There is no public confirmation of exploitation at the time of publication.
