What is the CVSS score of CVE-2025-40551?

CVE-2025-40551 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 80.6%.

Is there a public PoC exploit available for CVE-2025-40551?

Yes, a public proof-of-concept exploit is available for CVE-2025-40551. Prioritise patching immediately. EPSS: 80.6%.

How to fix or mitigate CVE-2025-40551?

Within 24 hours: Identify all SolarWinds Web Help Desk instances in your environment and isolate them from untrusted networks; disable external access and enable MFA on all administrative accounts. Within 7 days: Deploy network segmentation to restrict Web Help Desk traffic and implement Web Application Firewall (WAF) rules to block exploitation attempts; conduct forensic analysis of Web Help Desk logs for signs of compromise. Within 30 days: Monitor SolarWinds security advisories for patch availability and apply immediately upon release; evaluate alternative help desk solutions if patching timeline is unacceptable.

Web Help Desk CVE-2025-40551

CRITICAL

Deserialization of Untrusted Data (CWE-502)

2026-01-28 psirt@solarwinds.com

RCE Deserialization Web Help Desk Solarwinds

9.8

CVSS 3.1 · NVD

View

Vulnerability Assessment

Weakness	CWE CWE-502 OWASP Top 10:2025 A08:2025 - Software or Data Integrity Failures ASVS 5.0 V1 - Encoding and Sanitization Safe deserialization, type allowlists MITRE ATT&CK 2 techniques across 2 tactics: Execution, Initial Access The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS 9.8 (Critical). EPSS 80.6% — near-certain exploitation. KEV-listed — actively exploited. No authentication required. Trivially exploitable with public tooling (ysoserial). SolarWinds products are high-value APT targets. Chainable with CVE-2025-40536 for complete compromise.
Exploit ScenarioDerived	An attacker uses ysoserial or similar tool to generate a malicious Java serialized object containing a command execution gadget chain. This payload is sent to the Web Help Desk server via an unauthenticated HTTP request. The server deserializes the object, triggering execution of the embedded command (e.g., reverse shell, webshell deployment). The attacker gains command-line access to the WHD server, enabling data exfiltration, credential harvesting, and pivoting into the internal network.

Emergency Immediate action required. Why: CRITICAL + in CISA KEV (actively exploited), no patch available.

Exploited in the wild (CISA KEV) No patch listed yet 80.6% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 12, 2026

SolarWinds Web Help Desk contains an unauthenticated Java deserialization vulnerability (CVE-2025-40551, CVSS 9.8) that enables remote code execution. With EPSS 80.6% and KEV listing, this is the more severe of two concurrent WHD vulnerabilities, allowing attackers to execute arbitrary commands on the host server without any credentials.

Earlier versions of this analysis (1)

v1 Mar 12, 2026 - 21:54 CVSS 9.8

SolarWinds Web Help Desk processes untrusted serialized Java data without proper validation (CWE-502), allowing unauthenticated remote attackers to execute arbitrary code on the underlying server through crafted deserialization payloads.

RemediationAI

Apply SolarWinds security update immediately — this is highest priority. Take WHD offline if patching is delayed. Block external access to WHD. Monitor for Java deserialization attack indicators (unusual POST payloads, ysoserial signatures). Conduct incident response investigation to determine if exploitation has already occurred.

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

The application accepts serialized Java objects from unauthenticated HTTP requests. An attacker can construct a malicious serialized object using common Java deserialization gadget chains (such as those from Apache Commons Collections, Spring Framework, or other libraries bundled with WHD) that execute arbitrary OS commands when deserialized. The attack is straightforward with tools like ysoserial and requires no authentication or prior knowledge of the target beyond its URL.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 9.8 CRITICAL

AV:N/AC:L/PR:N/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

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Added to CISA KEV

Feb 04, 2026 - 02:00 cisa

CISA KEV

CVE Published

Jan 28, 2026 - 08:16 nvd

CRITICAL 9.8

DescriptionCVE.org

SolarWinds Web Help Desk was found to be susceptible to an untrusted data deserialization vulnerability that could lead to remote code execution, which would allow an attacker to run commands on the host machine. This could be exploited without authentication.

Executive ViewAI

Why It Matters

SolarWinds Web Help Desk contains a critical remote code execution vulnerability (CVE-2025-40551) that is actively being exploited in the wild and requires no authentication to attack. Any organization running this software faces immediate risk of complete system compromise, data theft, and operational disruption.

Business Impact: Severe

Compensating Controls

Implement network segmentation to restrict access to Web Help Desk to trusted internal networks only; deploy Web Application Firewall with rules blocking suspicious deserialization payloads and POST requests to vulnerable endpoints; disable Web Help Desk external access and enforce VPN-only connectivity; monitor logs for indicators of compromise including unusual process execution, command execution, and network connections from the application; consider running Web Help Desk in an isolated environment or air-gapped network until patch is available.

Threat Intelligence Overview

Threat Score

7.4/10

Composite threat intelligence

EPSS Score

80.6%

Top 1% exploitable

Exploit

POC

Public exploit code exists

Data Quality

5 sources

Confidence: Medium

NVD

CVE.org

CISA KEV

EPSS POC (2)

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 Yes

Public POC Yes

EPSS 80.6%

Patch available No

Active threat Yes

Deciding rule

CRITICAL + in CISA KEV (actively exploited), no patch available

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

Immediate

Exploitation· derived

Active

System Exposure· derived

Open

Automatable· derived

Yes

Human Impact

Very High

Priority Score

215

Low Medium High Critical

KEV: +50

EPSS: +81

CVSS: +49

PoC: +20

Weaponized: +15

Threat intel: 0

Gov advisory: 0

Attack Technique

Insecure Deserialization CRITICAL

Insecure deserialization occurs when an application converts serialized data (a stream of bytes representing an object's state) back into a living object without proper validation.

Remote Code Execution CRITICAL

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