CVE-2021-20683Network attack vector

Authenticated stored XSS via blog editor

Published Mar 26, 2021 · Updated Aug 3, 2024

Cross-site scripting in baserCMS blog article editing before 4.4.5 allows remote authenticated attackers to inject arbitrary scripts. The blog article editing function fails to neutralize JavaScript supplied through its input handling, allowing attacker-controlled script content to be stored or rendered. A remote authenticated user must reach the blog editor, and exploitation depends on a victim loading the affected article; the documented impact is script execution in that web context, with no evidence of direct server compromise.

CVSS severity3.5
Low
EPSS probability0.73%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in baserCMS blog article editing before 4.4.5 allows remote authenticated attackers to inject arbitrary scripts. The blog article editing function fails to neutralize JavaScript supplied through its input handling, allowing attacker-controlled script content to be stored or rendered. A remote authenticated user must reach the blog editor, and exploitation depends on a victim loading the affected article; the documented impact is script execution in that web context, with no evidence of direct server compromise.

The record

CVE
CVE-2021-20683
Published
Mar 26, 2021
Updated
Aug 3, 2024
Vendor
baserCMS Users Community
Product
baserCMS
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Mar 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=versions prior to 4.4.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

baserCMS Users Community · baserCMSversion=versions prior to 4.4.5

Published CVSS scores

3.5NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N

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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

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

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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