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Vulnerability report

Active exploitation observed Confirmed confidence Not in CISA KEV

CVE-2025-40553

Web Help Desk Deserialization

SolarWinds / Web Help Desk · 12.8.8 HF1 and below

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Severity
CVSS 9.8 · Critical
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
60.4%
First observed
18 Aug 2026
Last observed
01 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2025-40553 is an unauthenticated vulnerability affecting SolarWinds Web Help Desk. SolarWinds Web Help Desk was found to be susceptible to an untrusted data deserialization vulnerability that could lead to remote...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence.

Who is affected?

SolarWinds / Web Help Desk 12.8.8 hf1 and below.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Web Help Desk Deserialization

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.

Vendor Product Affected Status
SolarWinds Web Help Desk 12.8.8 HF1 and below Affected
Published
28 Jan 2026
Exploitation Reported
18 Aug 2026
Attack vector
Remote
Complexity
Low
Privileges
None
User interaction
None

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 18 Aug 2026

Independent exploitation attestation added to the Previdian record.

Active exploitation observed

Previdian sensor

First observed 18 Aug 2026

First-party sensor telemetry confirms matching exploitation attempts.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

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Source Added
Previdian First 2026-09-01 12:15 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Aggregate observations show the scale, recency, and distribution of activity without overstating sparse data.

31

Attempts observed

9

Unique attacker IPs

6

Attacker countries

CA · DE · GB · JP · SG · US

1

Sensors observed

Exploitation attempts over the last 17 days

Daily events observed by Previdian sensors

Updated 02 Sep 2026

0
12
0
0
0
0
0
0
1
0
0
12
0
0
0
6
0
17 Aug 21 Aug 25 Aug 29 Aug 2 Sep

First observed 18 Aug 2026 · Last observed 01 Sep 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
1
User-Agents
6

Raw values available in Pro and Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

No Previdian virtual patch is currently available. Future rules ship for ModSecurity, Cloudflare, and AWS WAF.

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Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS

60.4%

Weaknesses

Deserialization of Untrusted Data CWE-502

Timeline

From disclosure to observed exploitation

  1. Observed by Previdian sensors

    Evidence-backed exploitation signal

  2. Indicators of compromise added (9)

    Indicators of compromise recorded

  3. CVE published

    Vulnerability disclosed publicly

  4. CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2025-40553

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2025-40553",
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "cvss_estimated": false,
  "epss_score": 0.6039,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 31, "sensors": 1 }
}