CVE-2020-21146Public exploitNetwork attack vector

Stored JavaScript execution via unencoded signup username

Published Jan 21, 2021 · Updated Aug 4, 2024

Stored cross-site scripting in Feehi CMS 2.0.8 allows remote attackers to execute JavaScript in a post viewer's browser via a crafted username. The frontend User model returned stored username values without HTML encoding; post views then rendered those values, while the fix encodes the username in afterFind(). The attacker can register the crafted account without prior privileges, but a user must browse a post authored by that account before the script runs.

CVSS severity6.1
Medium
EPSS probability0.76%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored cross-site scripting in Feehi CMS 2.0.8 allows remote attackers to execute JavaScript in a post viewer's browser via a crafted username. The frontend User model returned stored username values without HTML encoding; post views then rendered those values, while the fix encodes the username in afterFind(). The attacker can register the crafted account without prior privileges, but a user must browse a post authored by that account before the script runs.

The record

CVE
CVE-2020-21146
Published
Jan 21, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 21, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

6.1GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/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.

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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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

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

Public exploit references

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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