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TOTOLINK X2000R CVE-2026-10136

| EUVDEUVD-2026-105327 CRITICAL
Heap-based Buffer Overflow (CWE-122)
2026-10-20 talos GHSA-6p6v-m5v6-qvwr
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
    Authenticate to router admin interface
  2. Delivery
    Send crafted HTTP request to formUpload()
  3. Exploit
    Overflow heap buffer in boa parser
  4. Execution
    Execute arbitrary code on device
  5. Impact
    Full router/network compromise

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Heap 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

Exploitation requires an authenticated HTTP request to the boa web server's formUpload() functionality on a TOTOLINK X2000R running firmware V1.0.0-B20250421.1327 - i.e. the attacker must already hold valid administrative/operator credentials for the router's web management interface (PR:H). The exploit is limited by this authentication requirement and by reachability of the management interface: devices whose admin panel is not exposed to untrusted networks and that use strong, unique credentials are substantially harder to attack. No user interaction is needed once authenticated, and attack complexity is low. The primary realistic exposure is routers with default/weak passwords or with the web UI reachable from the WAN or an untrusted LAN segment.

Impact

This is a genuinely serious vulnerability but not a blanket emergency. The vendor CVSS of 9.1 (AV:N/AC:L/PR:H/UI:N/S:C) reflects network-reachable, low-complexity arbitrary code execution, and CWE-122 (heap overflow) plus the explicit RCE tag align with that severity. The single most important mitigating signal is PR:H: the description confirms the attacker must make an *authenticated* HTTP request, so exploitation presupposes valid administrative credentials on the router's boa web interface. No EPSS score, CISA KEV entry, or public POC was supplied in the input, so there is no evidence of active exploitation or weaponization - this is a Talos-reported research finding (TALOS-2026-2436), which typically means coordinated disclosure rather than observed in-the-wild abuse. The practical risk is therefore high for any device where admin access is exposed or where default/weak credentials are in use (common on consumer routers), but meaningfully lower than an unauthenticated 9.1 would imply. Note a modeling tension: the vendor sets S:C (scope change), which is defensible for an embedded device where the web server runs as root and compromise affects the whole network boundary, but base RCE within the device's own security authority is often scored S:U - this inflates the score somewhat and should be verified against the Talos advisory.

Exploit ScenarioDerived

An attacker who has obtained administrative access to a TOTOLINK X2000R router (via default credentials, credential reuse, phishing, or an exposed management interface) sends a specially crafted HTTP request to the boa web server's formUpload() handler, overflowing a heap buffer. The corrupted heap is leveraged to execute arbitrary code on the device, yielding full control of the router. No public exploit code was identified at time of analysis, but Talos authored a detailed vulnerability report.

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 can trigger a heap-based buffer overflow in the boa web server's formUpload() handler on TOTOLINK X2000R routers running firmware V1.0.0-B20250421.1327, potentially leading to arbitrary code execution. The vulnerability requires valid administrative credentials (PR:H) but no user interaction, and the management interface must be network-reachable. No public exploit code or active exploitation has been identified at time of analysis.

RemediationAI

No vendor-released patch has been identified at time of analysis. Until a firmware update is available, restrict access to the router's web management interface to trusted networks only (e.g., firewall rules, VLAN segmentation, or disabling WAN-side remote management); this may impede legitimate remote administration but blocks the attack vector. Change default and weak administrative credentials to strong, unique passwords - while PR:H is required, compromised credentials are the primary enabler. Monitor HTTP logs for anomalous requests to formUpload() and consider disabling file upload functionality if the device permits. Consult the Talos advisory (https://talosintelligence.com/vulnerability_reports/TALOS-2026-2436) for updates.

Affected VersionsENISA

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

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The boa web server is a lightweight embedded HTTP daemon commonly used in routers and IoT devices; its formUpload() function processes multipart/form-data file uploads. CWE-122 (heap-based buffer overflow) indicates that user-controlled input is copied into a heap-allocated buffer without proper bounds validation, corrupting heap metadata and enabling arbitrary code execution. The CVSS vector AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H confirms network reachability, low attack complexity, high privileges required, and no user interaction. The CPE string cpe:2.3:a:totolink:totolink:*:*:*:*:*:*:*:* is a generic vendor-level entry; the confirmed affected version is TOTOLINK-X2000R-Gh-V1.0.0-B20250421.1327 per the Talos advisory TALOS-2026-2436.

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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 heap overflow needing admin authentication (PR:H); code executes within the device's own root authority so S:U, with full C/I/A impact on the compromised router.

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 heap-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

TOTOLINK X2000R routers running firmware V1.0.0-B20250421.1327 contain a critical heap-based buffer overflow in the boa web server's formUpload() handler that allows an authenticated administrative user to achieve arbitrary code execution when the management interface is network-reachable. This affects organizations with these routers exposed at the network edge or with shared administrative credentials, creating a risk of device compromise and potential lateral movement. Leadership should prioritize inventory and access restrictions because no vendor-released patch is identified and no public exploit identified at time of analysis.

Business Impact: High
Compensating Controls

No vendor-released patch identified at time of analysis; interim mitigations include restricting management interface access to trusted networks/IP allowlists, disabling WAN-side administration, enforcing strong unique administrative credentials, segmenting affected routers, monitoring administrative logins and configuration changes, and isolating or replacing devices that cannot be adequately protected.

Threat Intelligence Overview

EPSS Score
0.9%
Top 39% exploitable
Prevalence
Low
budget consumer/SOHO router brand, limited enterprise footprint
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
High

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 heap overflow occurs when a program writes data beyond the bounds of a buffer allocated in the heap memory region.

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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