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Tl Wr940n Firmware EUVDEUVD-2025-18451

| CVE-2025-6151 HIGH
Buffer Overflow (CWE-119)
2025-06-17 f23511db-6c3e-4e32-a477-6aa17d310630
8.2
CVSS 4.0 · NVD
View

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2021 - Vulnerable and Outdated Components
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, buffer size validation
MITRE ATT&CK

2 techniques across 2 tactics: Execution, Privilege Escalation

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

Impact

This vulnerability presents a nuanced risk profile. CVSS v4.0 score of 8.2 is elevated, but the vector reveals critical mitigating factors: AV:N (network-accessible), AC:L (low complexity), but PR:H (high privilege required) and UI:N. The PR:H requirement severely constrains exploitability—an attacker must already be authenticated with administrative credentials. Impact is primarily VA:H (availability), with no confidentiality or integrity compromise (VC:N, VI:N, SC:N, SI:N), indicating denial-of-service rather than data theft. Without EPSS data or KEV (Known Exploited Vulnerability) status provided, assessed likelihood of exploitation is low-to-moderate in practice: the high privilege barrier is a substantial control. However, this is an end-of-life product with no vendor support, meaning no patches will ever be released. For organizations still operating these devices, this represents a longer-term risk that can only be mitigated through hardware replacement.

Exploit ScenarioDerived

An attacker with legitimate administrative access (e.g., compromised credentials via phishing, insider threat, or from default credentials) navigates to the router's web interface and crafts a malicious HTTP request to /userRpm/WanSlaacCfgRpm.htm with an oversized payload in the SLAAC configuration parameters. This causes a buffer overflow in the firmware's CGI handler, corrupting adjacent memory and crashing the router (denial of service). In a worst-case scenario with favorable memory layout, this could enable code execution, though the PR:H requirement means pre-authentication is required, making worm-like propagation unlikely. Realistic attack vector involves targeted compromise of a specific organization's network infrastructure rather than widespread automated exploitation.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 14, 2026

Buffer overflow vulnerability in TP-Link TL-WR940N V4 and TL-WR841N V11 routers, exploitable remotely through the /userRpm/WanSlaacCfgRpm.htm endpoint. An attacker with high privileges can trigger memory corruption leading to availability impact (denial of service) or potential system compromise. This vulnerability affects end-of-life products no longer receiving vendor support, significantly limiting remediation options.

RemediationAI

primary: Hardware replacement; description: No patches will be released for these end-of-life products. Organizations should plan migration to current TP-Link models or alternative vendors with active security support. mitigation: Network segmentation; description: Restrict access to router management interface to trusted administrative networks only. Disable remote management (disable HTTP/HTTPS WAN access to admin interface) if supported. mitigation: Access control; description: Change default administrative credentials immediately. Ensure strong, unique passwords for all administrative accounts to reduce unauthorized access risk. mitigation: Monitoring; description: Monitor router logs for unusual administrative login attempts or configuration changes to /userRpm/WanSlaacCfgRpm.htm endpoint.

Affected VersionsENISA

TL-WR841N V11 0 ≤160325
TL-WR940N V4 0 ≤160617
TL-WR940N V4

Affected Packages

euvd tl_wr841n_v11 no fix
euvd tl_wr940n_v4 no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

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

Technical ContextAI · show details

The vulnerability exists in CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer), a classic buffer overflow class affecting memory safety. The vulnerable endpoint /userRpm/WanSlaacCfgRpm.htm handles SLAAC (Stateless Address AutoConfiguration) configuration in IPv6, likely processing user-supplied input without proper bounds checking. TP-Link router firmware typically uses embedded Linux with custom CGI handlers; this specific file is part of the web-based management interface. The affected products are: TP-Link TL-WR940N V4 (CPE: cpe:2.3:h:tp-link:tl-wr940n:4:*:*:*:*:*:*:*) and TP-Link TL-WR841N V11 (CPE: cpe:2.3:h:tp-link:tl-wr841n:11:*:*:*:*:*:*:*). Both are residential-grade wireless routers that reached end-of-life several years ago.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.2 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
High
User Interaction
None
Vulnerable system: Confidentiality
None
Vulnerable system: Integrity
None
Vulnerable system: Availability
High
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
High

Lifecycle Timeline

2
PoC Detected
Jul 15, 2025 - 19:15 vuln.today
Public exploit code
CVE Published
Jun 17, 2025 - 01:15 nvd
HIGH 8.2

DescriptionCVE.org

A vulnerability has been found in TP-Link TL-WR940N V4 and TL-WR841N V11. Affected by this issue is some unknown functionality of the file /userRpm/WanSlaacCfgRpm.htm, which may lead to buffer overflow. The attack may be launched remotely. This vulnerability only affects products that are no longer supported by the maintainer.

Executive ViewAI

Why It Matters

TP-Link routers TL-WR940N V4 and TL-WR841N V11 contain a critical buffer overflow vulnerability with active public exploits and no vendor patch available. Organizations using these unsupported devices face immediate risk of remote compromise, potentially enabling network intrusion, data theft, and lateral movement.

Business Impact: High
Compensating Controls

Disable WAN SLAAC configuration feature if functionality permits. Implement network segmentation to prevent direct access to affected devices from untrusted networks. Disable remote management and limit administrative access to trusted internal networks only. Deploy IDS/IPS rules to detect buffer overflow exploitation attempts targeting /userRpm/WanSlaacCfgRpm.htm. Consider upgrading to supported TP-Link router firmware versions or replacing devices with current-generation equipment receiving active vendor support.

Threat Intelligence Overview

EPSS Score
0.5%
Top 33% exploitable
Exploit
POC
Public exploit code exists
Data Quality
6 sources
Confidence: High

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 HIGH
CISA KEV No
Public POC Yes
EPSS 0.5%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
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
Poc
System Exposure· derived
Open
Automatable· derived
No
Human Impact
High

Priority Score

62
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +41
PoC: +20
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.

CVE-2023-36355 CRITICAL POC
9.9 Jun 22

TP-Link TL-WR940N V4 was discovered to contain a buffer overflow via the ipStart parameter at /userRpm/WanDynamicIpV6Cfg

CVE-2023-33538 HIGH POC
8.8 Jun 07

TP-Link TL-WR940N V2/V4, TL-WR841N V8/V10, and TL-WR740N V1/V2 was discovered to contain a command injection vulnerabili

CVE-2019-6989 HIGH POC
8.8 Jun 06

TP-Link TL-WR940N is vulnerable to a stack-based buffer overflow, caused by improper bounds checking by the ipAddrDispos

CVE-2023-33537 HIGH POC
8.1 Jun 07

TP-Link TL-WR940N V2/V4, TL-WR841N V8/V10, and TL-WR740N V1/V2 was discovered to contain a buffer overflow via the compo

CVE-2023-33536 HIGH POC
8.1 Jun 07

TP-Link TL-WR940N V2/V4, TL-WR841N V8/V10, and TL-WR740N V1/V2 was discovered to contain a buffer overflow via the compo

CVE-2023-36358 HIGH POC
7.7 Jun 22

TP-Link TL-WR940N V2/V3/V4, TL-WR941ND V5/V6, TL-WR743ND V1 and TL-WR841N V8 were discovered to contain a buffer overflo

CVE-2023-36357 HIGH POC
7.7 Jun 22

An issue in the /userRpm/LocalManageControlRpm component of TP-Link TL-WR940N V2/V4/V6, TL-WR841N V8/V10, and TL-WR941ND

CVE-2023-36356 HIGH POC
7.7 Jun 22

TP-Link TL-WR940N V2/V4/V6, TL-WR841N V8, TL-WR941ND V5, and TL-WR740N V1/V2 were discovered to contain a buffer read ou

CVE-2023-36359 HIGH POC
7.5 Jun 22

TP-Link TL-WR940N V4, TL-WR841N V8/V10, TL-WR940N V2/V3 and TL-WR941ND V5/V6 were discovered to contain a buffer overflo

CVE-2023-36354 HIGH POC
7.5 Jun 22

TP-Link TL-WR940N V4, TL-WR841N V8/V10, TL-WR740N V1/V2, TL-WR940N V2/V3, and TL-WR941ND V5/V6 were discovered to contai

CVE-2022-24355 HIGH
8.8 Feb 18

This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of TP-Link TL-W

CVE-2024-54887 HIGH
8.0 Jan 09

TP-Link TL-WR940N V3 and V4 with firmware 3.16.9 and earlier contain a buffer overflow via the dnsserver1 and dnsserver2

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