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TOTOLINK X2000R CVE-2026-10137

| EUVDEUVD-2026-105326 CRITICAL
Stack-based Buffer Overflow (CWE-121)
2026-10-20 talos GHSA-mc64-wjc4-x653
9.1
CVSS 3.1 · Vendor: talos
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Obtain/abuse valid admin credentials
  2. Delivery
    Reach boa web interface over HTTP
  3. Exploit
    Send crafted formUpload request
  4. Execution
    Overflow stack buffer (CWE-121)
  5. Impact
    Execute arbitrary code as root

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Stack buffer bounds checking
MITRE ATT&CK

1 technique across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Requires valid authenticated access to the X2000R device's boa-based web administration interface (PR:H), from which the attacker sends a crafted HTTP request to the formUpload() functionality to trigger the stack overflow. No user interaction is needed (UI:N) and complexity is low (AC:L) once authenticated. The primary limiting factor is credential access: exploitation is gated behind router admin login, so realistic risk hinges on whether the device uses default/weak credentials or is reachable from an attacker-controlled network segment. Confirmed affected firmware is TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327; applicability to other versions is not stated.

Impact

This is a high-severity but access-gated vulnerability. The CVSS 3.1 vector (AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H, score 9.1) indicates a network-reachable, low-complexity flaw with full confidentiality, integrity, and availability impact - but critically it requires PR:H, and the Talos description explicitly confirms 'an authenticated HTTP request' is needed. This single prerequisite substantially lowers real-world risk versus a true unauthenticated RCE, since an attacker must already hold valid credentials (or chain a separate auth bypass / use default/weak router passwords). No EPSS score, CISA KEV listing, or public POC is present in the provided data, so there is no evidence of active exploitation or mass scanning at this time. One notable conflict: the input vector asserts S:C (scope changed), yet a stack overflow in the boa web server typically yields code execution within that same (already highly privileged, usually root) component without crossing a security authority boundary - the scope-changed rating may be inflated. Overall this is a credible high-impact router RCE suitable for prioritized patching on exposed/managed TOTOLINK fleets, but the authentication requirement makes it a targeted-abuse or post-credential-compromise issue rather than an internet-wide wormable threat.

Exploit ScenarioDerived

An attacker who has obtained valid credentials for a TOTOLINK X2000R admin interface (via default/weak passwords, phishing, or reuse) sends a specially crafted HTTP request to the boa web server's formUpload() handler, overflowing a stack buffer and gaining arbitrary code execution - typically as root - on the router. No public exploit code is identified at time of analysis, though a detailed Talos vulnerability report exists. Because the CVSS vector is AV:N/AC:L with no user interaction, the request itself is trivial to deliver once authenticated.

Act Now Prioritize within 24-48h. Why: CRITICAL severity.
No patch listed yet 0.9% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 20, 2026

Authenticated attackers who can reach the boa web administration interface on TOTOLINK X2000R firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 can trigger a stack-based buffer overflow by sending a crafted HTTP request to formUpload(), with potential for arbitrary code execution and high confidentiality, integrity, and availability impact. The issue is access-gated: exploitation requires high-privilege router administrator credentials (PR:H) and low complexity once authenticated (AC:L/UI:N), so realistic risk depends on whether the management UI is exposed and protected by default or weak credentials. No public exploit code or CISA KEV active-exploitation listing was identified in the provided data.

RemediationAI

No vendor-released patch was identified at time of analysis; monitor the Talos advisory at https://talosintelligence.com/vulnerability_reports/TALOS-2026-2437 and TOTOLINK support channels for a fixed firmware release. Until a patch is available, remove exposure of the boa web administration interface: disable WAN-side remote management (trade-off: loses remote administrative access), restrict the management UI to a trusted VLAN or VPN with firewall allowlisting (trade-off: administration requires VPN or trusted network access), and replace default or weak administrator credentials with strong unique passwords (trade-off: credential management overhead, but directly addresses the PR:H gate). As a narrower control, use a reverse proxy or WAF to restrict or block multipart upload requests to the formUpload() handler (trade-off: may break legitimate firmware or configuration uploads). Monitor device logs for unexpected authenticated upload requests and unusual crashes or restarts.

Affected VersionsENISA

Totolink TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327

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Technical ContextAI · show details

TOTOLINK X2000R routers use the boa embedded HTTP server for their web management interface. The formUpload() function handles HTTP upload requests and copies attacker-controlled input into a fixed-size stack buffer without adequate bounds checking, the classic CWE-121 stack-based buffer overflow condition. A crafted HTTP request can overwrite stack memory and potentially redirect execution, leading to arbitrary code execution in the context of the boa service on the device. The supplied CPE entry cpe:2.3:a:totolink:totolink:*:*:*:*:*:*:*:* is vendor-wide rather than version-specific; the confirmed affected firmware in the report is TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327. The assessed CVSS vector is CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, indicating network reachability but high privileges required, so the overflow is only reachable after authenticating to the administrative interface.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (talos) PRIMARY 9.1 CRITICAL
AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
vuln.today AI 7.2 HIGH

Network-reachable, low-complexity overflow needing admin authentication (PR:H); full C/I/A impact as root, but scope assessed Unchanged since code executes within the boa web server itself, unlike the input's S:C.

3.1 AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (talos).

CVSS VectorVendor: talos

Attack Vector
Network
Attack Complexity
Low
Privileges Required
High
User Interaction
None
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

A stack-based buffer overflow vulnerability exists in the boa formUpload() functionality of X2000R (version(s): 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 this vulnerability.

Executive ViewAI

Why It Matters

The TOTOLINK X2000R router (firmware TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327) carries a critical memory-corruption flaw in the formUpload() handler of its web administration interface, allowing a logged-in administrator to crash or potentially take full control of the device. Because the prerequisite is already-high-privilege router credentials, the practical exposure concentrates on units whose management UI is reachable from untrusted networks or still protected by default or shared passwords - typically home-office and small-branch gateways that leadership may not track as managed assets. A compromised gateway sits in the path of all traffic for the sites it serves, so unmanaged or internet-exposed units warrant attention despite the credential gate. No vendor fix is available at time of analysis and no public exploit has been identified.

Business Impact: Medium
Compensating Controls

No vendor-released patch identified at time of analysis. Interim mitigations: remove or firewall the web administration interface from WAN and untrusted segments, restrict management to a dedicated VLAN or jump host with allow-listed source addresses, enforce strong unique administrator credentials and rotate them, disable remote management and UPnP, monitor authentication and configuration-change logs, and retire or replace units that cannot be isolated.

Threat Intelligence Overview

EPSS Score
0.9%
Top 39% exploitable
Prevalence
Low
consumer/SOHO router brand, limited enterprise footprint, concentrated regionally
Data Quality
4 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity CRITICAL
CISA KEV No
Public POC No
EPSS 0.9%
Patch available No
Active threat No
Deciding rule
CRITICAL severity
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Medium

Priority Score

47
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +46
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

A stack-based buffer overflow occurs when a program writes more data to a buffer located on the stack than it was allocated to hold.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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