CVE-2024-4023Public exploitNetwork attack vector

Stored XSS via permitted .xsig uploads

Published Mar 20, 2025 · Updated Mar 20, 2025

Stored cross-site scripting in the FlatPress uploader before 1.3 allows attackers to run JavaScript through a crafted .xsig file. The uploader denylist omits the xsig extension, while direct retrieval serves the uploaded file as application/octet-stream and browsers process its markup. Exploitation requires a user to upload and directly open the file; the script then runs in the same-origin context and can access cookies and content or issue requests.

CVSS severity8.1
High
EPSS probability0.78%
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 the FlatPress uploader before 1.3 allows attackers to run JavaScript through a crafted .xsig file. The uploader denylist omits the xsig extension, while direct retrieval serves the uploaded file as application/octet-stream and browsers process its markup. Exploitation requires a user to upload and directly open the file; the script then runs in the same-origin context and can access cookies and content or issue requests.

The record

CVE
CVE-2024-4023
Published
Mar 20, 2025
Updated
Mar 20, 2025
Vendor
FlatPress
Product
FlatPress
Classifications
CWE-79, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2025Record 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=unspecified <1.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

FlatPress · FlatPressversion=unspecified <1.3

Published CVSS scores

8.1huntr CNACVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H

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
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1189Drive-by Compromise

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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