CVE-2021-35240

Browser script execution via Help Server setting

Published Aug 31, 2021 · Updated Aug 4, 2024

Stored XSS in the Help Server setting in SolarWinds Platform 2020.2.5 and earlier allows remote authenticated users to store browser script. The setting persists attacker-controlled content for later rendering, and the resulting new-window link depends on rel=noopener, which Internet Explorer does not support. Exploitation requires high privileges, adjacent-network access, and user interaction, enabling script execution in the Internet Explorer session.

CVSS severity6.5
Medium
EPSS probability1.07%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the Help Server setting in SolarWinds Platform 2020.2.5 and earlier allows remote authenticated users to store browser script. The setting persists attacker-controlled content for later rendering, and the resulting new-window link depends on rel=noopener, which Internet Explorer does not support. Exploitation requires high privileges, adjacent-network access, and user interaction, enabling script execution in the Internet Explorer session.

The record

CVE
CVE-2021-35240
Published
Aug 31, 2021
Updated
Aug 4, 2024
Vendor
SolarWinds
Product
SolarWinds Platform
Classifications
CWE-79, T1059.007
Attack vector
adjacent
Privileges
admin

Timeline

How it unfolded

  1. Aug 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2020.2.6 and previous versions <2020.2.6 HF1

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesadmin

What is affected?

SolarWinds · SolarWinds Platformversion=2020.2.6 and previous versions <2020.2.6 HF1

Published CVSS scores

4.8NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
3.5NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
6.5SolarWindsCVSS:3.1/AV:A/AC:H/PR:H/UI:R/S:C/C:H/I:L/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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