CVE-2020-11026Network attack vector

Stored XSS via incomplete UTF-8 filename sanitization

Published Apr 30, 2020 · Updated Aug 4, 2024

Stored cross-site scripting in WordPress 3.7 through 5.4 allows remote authenticated users to execute script via crafted media filenames. The sanitize_file_name function failed to normalize invalid UTF-8 bytes before accepting a stored filename, allowing browser-interpreted content to survive sanitization. An authenticated account with media-upload privileges must store the file, and script runs only when the uploaded file is accessed in a browser.

CVSS severity5.4
Medium
EPSS probability2.09%
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 WordPress 3.7 through 5.4 allows remote authenticated users to execute script via crafted media filenames. The sanitize_file_name function failed to normalize invalid UTF-8 bytes before accepting a stored filename, allowing browser-interpreted content to survive sanitization. An authenticated account with media-upload privileges must store the file, and script runs only when the uploaded file is accessed in a browser.

The record

CVE
CVE-2020-11026
Published
Apr 30, 2020
Updated
Aug 4, 2024
Vendor
WordPress.org
Product
WordPress
Classifications
CWE-79, CWE-707, T1189
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 30, 2020CVE 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

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=>= 3.7.0, < 3.7.33
  2. Affected versionversion=>= 3.8.0, < 3.8.33
  3. Affected versionversion=>= 3.9.0, < 3.9.31
  4. Affected versionversion=>= 4.0.0, < 4.0.30
  5. Affected versionversion=>= 4.1.0, < 4.1.30
  6. Affected versionversion=>= 4.2.0, < 4.2.27
  7. Affected versionversion=>= 4.3.0, < 4.3.23
  8. Affected versionversion=>= 4.4.0, < 4.4.22
  9. Affected versionversion=>= 4.5.0, < 4.5.21
  10. Affected versionversion=>= 4.6.0, < 4.6.18
  11. Affected versionversion=>= 4.7.0, < 4.7.17
  12. Affected versionversion=>= 4.8.0, < 4.8.13
  13. Affected versionversion=>= 4.9.0, < 4.9.14
  14. Affected versionversion=>= 5.0.0, < 5.0.9
  15. Affected versionversion=>= 5.1.0, < 5.1.5
  16. Affected versionversion=>= 5.2.0, < 5.2.6
  17. Affected versionversion=>= 5.3.0, < 5.3.3
  18. Affected versionversion=>= 5.4.0, < 5.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

WordPress.org · WordPressversion=>= 3.7.0, < 3.7.33; version=>= 3.8.0, < 3.8.33; version=>= 3.9.0, < 3.9.31; version=>= 4.0.0, < 4.0.30; version=>= 4.1.0, < 4.1.30; version=>= 4.2.0, < 4.2.27; version=>= 4.3.0, < 4.3.23; version=>= 4.4.0, < 4.4.22; version=>= 4.5.0, < 4.5.21; version=>= 4.6.0, < 4.6.18; version=>= 4.7.0, < 4.7.17; version=>= 4.8.0, < 4.8.13; version=>= 4.9.0, < 4.9.14; version=>= 5.0.0, < 5.0.9; version=>= 5.1.0, < 5.1.5; version=>= 5.2.0, < 5.2.6; version=>= 5.3.0, < 5.3.3; version=>= 5.4.0, < 5.4.1

Published CVSS scores

8.7GitHub Security AdvisoriesCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N
5.4NIST NVDCVSS: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')
CWE-707Improper Neutralization
T1189Drive-by Compromise

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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