What is the CVSS score of CVE-2026-0840?

CVE-2026-0840 has a CVSS 3.1 base score of 8.8 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Is there a public PoC exploit available for CVE-2026-0840?

Yes, a public proof-of-concept exploit is available for CVE-2026-0840. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-0840?

Within 7 days: Identify all affected systems and apply vendor patches promptly. Monitor vendor channels for patch availability.

520w Firmware CVE-2026-0840

HIGH

Buffer Overflow (CWE-119)

2026-01-11 cna@vuldb.com

Buffer Overflow 520w Firmware Utt

8.8

CVSS 3.1 · NVD

View

Attack ChainAIDerived

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

Access

Authenticate to device web interface
Exploit

Send crafted POST to /goform/formConfigNoticeConfig
Execution

Overflow timestart parameter in strcpy
Impact

Execute arbitrary code with device privileges

Vulnerability Assessment

Weakness	CWE CWE-119 OWASP Top 10:2025 A06:2021 - Vulnerable and Outdated Components ASVS 5.0 V15 - Secure Coding and Architecture Bounds checking, buffer size validation MITRE ATT&CK 2 techniques across 2 tactics: Execution,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. Sign in to read
Exploitation Conditions	Authenticated access to UTT 进取 520W device running version 1.7.7-180627 or earlier. Attacker requires valid login credentials to access the vulnerable /goform/formConfigNoticeConfig endpoint.
Impact	CVSS 8.8 (HIGH). Attack vector: Network. Complexity: Low. Privileges required: Low. User interaction: None. Exploitable via remote/network. Public exploit/POC available.
Exploit ScenarioDerived	A remote attacker could exploit this flaw, buffer overflow.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

Remote code execution in UTT 520W firmware (version 1.7.7-180627) via a stack buffer overflow in the /goform/formConfigNoticeConfig endpoint allows unauthenticated attackers to execute arbitrary code with full system privileges. Public exploit code exists for this vulnerability and the vendor has not released a patch despite early notification. An attacker can trigger the overflow by manipulating the timestart parameter through a network request.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 8.8

A security vulnerability has been detected in UTT 进取 520W 1.7.7-180627. Affected by this vulnerability is the function strcpy of the file /goform/formConfigNoticeConfig. [CVSS 8.8 HIGH]

RemediationAI

Monitor vendor advisories for a patch. Enable ASLR, DEP/NX, and stack canaries where possible. Restrict network access to the affected service where possible.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

Classified as CWE-119 (Buffer Overflow). Affects 520W Firmware. A security vulnerability has been detected in UTT 进取 520W 1.7.7-180627. Affected by this vulnerability is the function strcpy of the file /goform/formConfigNoticeConfig. The manipulation of the argument timestart leads to buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH

AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

PoC Detected

Jan 13, 2026 - 21:56 vuln.today

Public exploit code

CVE Published

Jan 11, 2026 - 07:15 nvd

HIGH 8.8

DescriptionCVE.org

A security vulnerability has been detected in UTT 进取 520W 1.7.7-180627. Affected by this vulnerability is the function strcpy of the file /goform/formConfigNoticeConfig. The manipulation of the argument timestart leads to buffer overflow. It is possible to initiate the attack remotely. The exploit has been disclosed publicly and may be used. The vendor was contacted early about this disclosure but did not respond in any way.

Executive ViewAI

Why It Matters

Organizations using A security vulnerability face significant risk from CVE-2026-0840, a buffer overflow vulnerability rated CVSS 8.8. Exploitation could allow attackers to corrupt memory, crash the application, or potentially execute arbitrary code. Proof-of-concept code is publicly available, increasing the risk of exploitation. Organizations should apply vendor updates when available and consider compensating controls in the interim.

Business Impact: Severe

Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Implement network-level access controls to limit exposure; (2) Enable enhanced monitoring and alerting; (3) Apply principle of least privilege.

Threat Intelligence Overview

EPSS Score

0.1%

Top 68% exploitable

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

EPSS

GitHub

VulDB

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 0.1%

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

Out-of-Cycle

Exploitation· derived

Poc

System Exposure· derived

Open

Automatable· derived

Human Impact

Very High

Priority Score

Low Medium High Critical

KEV: 0

EPSS: 0

CVSS: +44

PoC: +20

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Buffer Overflow HIGH

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.