What is CVE-2021-29447?

CVE-2021-29447 is a high-severity vulnerability in WordPress, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 7.1/10. Published 2021-04-15.

How severe is CVE-2021-29447?

High severity. CVSS v3 base score is 7.1 out of 10.

Is CVE-2021-29447 known to be exploited?

136 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

XXE in WordPress

CVE-2021-29447

Wordpress is an open source CMS. A user with the ability to upload files (like an Author) can exploit an XML parsing issue in the Media Library leading to XXE attacks. This requires WordPress installation to be using PHP 8. Access to internal files is possible in a successful XXE attack. This has been patched in WordPress version 5.7.1, along with the older affected versions via a minor release. We strongly recommend you keep auto-updates enabled.

Vulnerability class: XXE (XML External Entity)

Published 2021-04-15 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N.

EPSS exploit prediction

EPSS: 0.857 (99.7th percentile), scored 2026-10-19.

High probability of exploitation in the next 30 days — patch promptly. 100th percentile — 99.7% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.857 · newest: 0.857 · change: 0.000

Affected products

WordPress
WordPress Wordpress-Develop — versions >= 5.6.0, < 5.7.1
Debian Linux — versions 9.0, 10.0

Weakness classification (CWE)

CWE-611 — Improper Restriction of XML External Entity Reference (XXE)

Public proof-of-concept exploits

References

github.com/WordPress/wordpress-develop/security/advisories/GHSA-rv47-pc52-qrhh (Third Party Advisory)
wordpress.org/news/category/security/ (Release Notes, Vendor Advisory)
lists.debian.org/debian-lts-announce/2021/04/msg00017.html (mailing-list, Mailing List, Third Party Advisory)
www.debian.org/security/2021/dsa-4896 (vendor-advisory, Third Party Advisory)
packetstormsecurity.com/files/163148/XML-External-Entity-Via-MP3-File-Upload-On… (VDB Entry, Third Party Advisory)
packetstormsecurity.com/files/164198/WordPress-5.7-Media-Library-XML-Injection… (Exploit, VDB Entry, Third Party Advisory)
blog.sonarsource.com/wordpress-xxe-security-vulnerability/ (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2021-29447?: CVE-2021-29447 is a high-severity vulnerability in WordPress, classified under Improper Restriction of XML External Entity Reference (XXE). CVSS score: 7.1/10. Published 2021-04-15.
How severe is CVE-2021-29447?: High severity. CVSS v3 base score is 7.1 out of 10.
Is CVE-2021-29447 known to be exploited?: 136 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.