CVE-2021-43633Public exploitNetwork attack vector

Recipient script execution via unneutralized chat messages

Published Apr 14, 2022 · Updated Aug 4, 2024

Stored XSS in Sourcecodester Messaging Web Application 1.0 allows remote authenticated users to execute scripts in a recipient's browser. The chat message path stores sender-supplied script markup and renders it in the receiver's conversation view without neutralizing executable content. A registered sender must deliver a crafted message, and a receiver must open the affected chat; script execution remains within the application origin.

CVSS severity5.4
Medium
EPSS probability0.57%
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 Sourcecodester Messaging Web Application 1.0 allows remote authenticated users to execute scripts in a recipient's browser. The chat message path stores sender-supplied script markup and renders it in the receiver's conversation view without neutralizing executable content. A registered sender must deliver a crafted message, and a receiver must open the affected chat; script execution remains within the application origin.

The record

CVE
CVE-2021-43633
Published
Apr 14, 2022
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-79, T1203
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 14, 2022CVE 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 privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1203Exploitation for Client Execution

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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