CVE-2021-35217Network attack vector

Authenticated code execution via unsafe task deserialization

Published Sep 8, 2021 · Updated Sep 16, 2024

Insecure deserialization in SolarWinds Platform 2020.2.5 and earlier allows remote authenticated users to execute arbitrary code. The WSAsyncExecuteTasks endpoint accepts user-supplied serialized data without proper validation and deserializes it. Exploitation requires authentication and runs attacker-controlled code in the NETWORK SERVICE context.

CVSS severity8.9
High
EPSS probability72.79%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insecure deserialization in SolarWinds Platform 2020.2.5 and earlier allows remote authenticated users to execute arbitrary code. The WSAsyncExecuteTasks endpoint accepts user-supplied serialized data without proper validation and deserializes it. Exploitation requires authentication and runs attacker-controlled code in the NETWORK SERVICE context.

The record

CVE
CVE-2021-35217
Published
Sep 8, 2021
Updated
Sep 16, 2024
Vendor
SolarWinds
Product
SolarWinds Platform
Classifications
CWE-502, T1210
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 8, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 16, 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=2020.2.5 and previous versions <2020.2.6

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SolarWinds · SolarWinds Platformversion=2020.2.5 and previous versions <2020.2.6

Published CVSS scores

8.9SolarWindsCVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:L
8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-502Deserialization of Untrusted Data
T1210Exploitation of Remote Services

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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