CVE-2022-4821Network attack vector

Stored XSS via permitted XML and Markdown uploads

Published Dec 28, 2022 · Updated Aug 3, 2024

Stored XSS in FlatPress uploader allows remote authenticated users to execute JavaScript through uploaded XML or Markdown files. The onupload function in admin/panels/uploader/admin.uploader.php omits XML and Markdown from its extension blacklist and moves accepted files into the attachments directory. An administrative login is required to upload the file, and code runs only when a user opens the stored attachment in a browser.

CVSS severity2.4
Low
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Stored XSS in FlatPress uploader allows remote authenticated users to execute JavaScript through uploaded XML or Markdown files. The onupload function in admin/panels/uploader/admin.uploader.php omits XML and Markdown from its extension blacklist and moves accepted files into the attachments directory. An administrative login is required to upload the file, and code runs only when a user opens the stored attachment in a browser.

The record

CVE
CVE-2022-4821
Published
Dec 28, 2022
Updated
Aug 3, 2024
Vendor
FlatPress
Product
FlatPress
Classifications
CWE-79, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 28, 2022CVE 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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

FlatPress · FlatPressversion=n/a

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
2.4VulDBCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/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 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-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1059.007Command and Scripting Interpreter: JavaScript/JScript

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo