CVE-2020-4049Network attack vector

Administrator self-XSS via unescaped broken theme name

Published Jun 12, 2020 · Updated Aug 4, 2024

Cross-site scripting in affected WordPress releases allows administrators to execute JavaScript via a crafted theme folder name. The broken-theme row in wp-admin/themes.php prints get_stylesheet() directly when a theme lacks a Name value, without HTML-escaping the folder-derived string. Exploitation requires an administrator to upload the crafted theme and open the Themes page, so script execution is confined to that administrator's browser session.

CVSS severity2.4
Low
EPSS probability2.53%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cross-site scripting in affected WordPress releases allows administrators to execute JavaScript via a crafted theme folder name. The broken-theme row in wp-admin/themes.php prints get_stylesheet() directly when a theme lacks a Name value, without HTML-escaping the folder-derived string. Exploitation requires an administrator to upload the crafted theme and open the Themes page, so script execution is confined to that administrator's browser session.

The record

CVE
CVE-2020-4049
Published
Jun 12, 2020
Updated
Aug 4, 2024
Vendor
WordPress.org
Product
WordPress
Classifications
CWE-79, CWE-80, T1059.007
Attack vector
network
Privileges
admin

Timeline

How it unfolded

  1. Jun 12, 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, < 3.7.34
  2. Affected versionversion=>= 3.8.0, < 3.8.34
  3. Affected versionversion=>= 3.9.0, < 3.9.32
  4. Affected versionversion=>= 4.0.0, < 4.0.31
  5. Affected versionversion=>= 4.1.0, < 4.1.31
  6. Affected versionversion=>= 4.2.0, < 4.2.28
  7. Affected versionversion=>= 4.3.0, < 4.3.24
  8. Affected versionversion=>= 4.4.0, < 4.4.23
  9. Affected versionversion=>= 4.5.0, < 4.5.22
  10. Affected versionversion=>= 4.6.0, < 4.6.19
  11. Affected versionversion=>= 4.7.0, < 4.7.18
  12. Affected versionversion=>= 4.8.0, < 4.8.14
  13. Affected versionversion=>= 4.9.0, < 4.9.15
  14. Affected versionversion=>= 5.0.0, < 5.0.10
  15. Affected versionversion=>= 5.1.0, < 5.1.6
  16. Affected versionversion=>= 5.2.0, < 5.2.7
  17. Affected versionversion=>= 5.3.0, < 5.3.4
  18. Affected versionversion=>= 5.4.0, < 5.4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesadmin

What is affected?

WordPress.org · WordPressversion=>= 3.7.0, < 3.7.34; version=>= 3.8.0, < 3.8.34; version=>= 3.9.0, < 3.9.32; version=>= 4.0.0, < 4.0.31; version=>= 4.1.0, < 4.1.31; version=>= 4.2.0, < 4.2.28; version=>= 4.3.0, < 4.3.24; version=>= 4.4.0, < 4.4.23; version=>= 4.5.0, < 4.5.22; version=>= 4.6.0, < 4.6.19; version=>= 4.7.0, < 4.7.18; version=>= 4.8.0, < 4.8.14; version=>= 4.9.0, < 4.9.15; version=>= 5.0.0, < 5.0.10; version=>= 5.1.0, < 5.1.6; version=>= 5.2.0, < 5.2.7; version=>= 5.3.0, < 5.3.4; version=>= 5.4.0, < 5.4.2

Published CVSS scores

2.4GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N
2.4NVDCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:U/C:N/I:L/A:N
3.5NVDAV: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
T1059.007JavaScript/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

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Your stack

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