What is CVE-2026-71573?

CVE-2026-71573 is a high-severity vulnerability in Joomla Joomla\!, classified under CRLF Injection. CVSS score: 8.3/10. Published 2026-08-18.

How severe is CVE-2026-71573?

High severity. CVSS v3 base score is 8.3 out of 10.

Vulnerability in Joomla Joomla\!

CVE-2026-71573

Joomla! Core - [20260802] - Improper CORS origin validation in Joomla 4.0.0-5.4.7, 6.0.0-6.1.2 - An improper implementation prevented configured CORS origins from being properly validated in CORS requests.

Vulnerability class: CRLF Injection

Published 2026-08-18 · last modified 2026-09-03.

CVSS v3 metric

CVSS v3 base score 8.3 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L.

EPSS exploit prediction

EPSS: 0.003 (25.3th percentile), scored 2026-10-02.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.000

Affected products

Joomla Joomla\!
Joomla! Project Cms — versions 4.0.0-5.4.6, 6.0.0-6.1.2

Weakness classification (CWE)

CWE-93 — CRLF Injection

References

www.joomla.org/ (Product, product)
developer.joomla.org/security-centre/20260802-core-improper-cors-origin-validat… (vendor-advisory, Broken Link, Vendor Advisory)

Frequently asked questions

What is CVE-2026-71573?: CVE-2026-71573 is a high-severity vulnerability in Joomla Joomla\!, classified under CRLF Injection. CVSS score: 8.3/10. Published 2026-08-18.
How severe is CVE-2026-71573?: High severity. CVSS v3 base score is 8.3 out of 10.