How do I check whether I am affected by CVE-2026-42020?

In the router web UI (System/Status page) read the firmware version; affected if it is TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. Also check whether the admin web interface (boa) is reachable from WAN.

What is the fix for CVE-2026-42020?

No fixed firmware published as of 2026-10-23 (unknown). Check TOTOLINK's download page for X2000R. Mitigate: disable WAN/remote management, restrict the admin UI to a trusted LAN, change the default admin password, and avoid IPv6 PPPoE setup from untrusted users.

Who is not affected by CVE-2026-42020?

Not affected if: auth-required, remote-management-disabled.

Live › vulnerability › CVE-2026-42020

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critical9.1Infrastructure

Totolink X2000R router: stack overflow in IPv6 PPPoE setup lets attackers run code

Stack buffer overflows in the boa web server's formIpv6Setup PPPoE handler (pppoe_dns2 parameter) on Totolink X2000R firmware B20250421.1327 allow code execution via a crafted HTTP request. Requires admin login (CVSS 9.1, PR:H); no fix or public exploit known.

Summary written from the sources below. Check the originals before acting.

CVSS 3.x

9.1

critical

scored by [email protected]

known so far5 of 6

missing: exploitation

First public: Oct 20, 2026 UTC
Last modified: Oct 23, 2026
Status: open
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.

Why it is critical, and not just CVSS

Likelihood → · Impact ↓

critical

high

medium

high

medium

low

medium

low

Exploited: No reports yet.
Needs login: Yes.
Needs a special setup: Not known from the sources.
Reachable from: network.
Worst case: Attacker runs code on the router as the device admin.
CVSS said: 9.1. The facts above say medium; we keep the sources' critical until an analyst looks.

Who is affected

1 product

Know the next one before it finds you.

Add to Slack

Live › vulnerability › CVE-2026-42020

Go to dashboard

critical9.1Infrastructure

Totolink X2000R router: stack overflow in IPv6 PPPoE setup lets attackers run code

Summary written from the sources below. Check the originals before acting.

CVSS 3.x

9.1

critical

scored by [email protected]

known so far5 of 6

missing: exploitation

First public: Oct 20, 2026 UTC
Last modified: Oct 23, 2026
Status: open
Known exploitation: None reported
Public exploit: None on GitHub
EPSS: not scored

First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.

Why it is critical, and not just CVSS

Likelihood → · Impact ↓

critical

high

medium

high

medium

low

medium

low

Exploited: No reports yet.
Needs login: Yes.
Needs a special setup: Not known from the sources.
Reachable from: network.
Worst case: Attacker runs code on the router as the device admin.
CVSS said: 9.1. The facts above say medium; we keep the sources' critical until an analyst looks.

Who is affected

1 product

Know the next one before it finds you.

Add to Slack

Totolink X2000R router: stack overflow in IPv6 PPPoE setup lets attackers run code

Why it is critical, and not just CVSS

Who is affected

Know the next one before it finds you.

Totolink X2000R router: stack overflow in IPv6 PPPoE setup lets attackers run code

Why it is critical, and not just CVSS

Who is affected

Know the next one before it finds you.

How to check

The fix

Who had it, and when

What the sources say, verbatim

Sources