# CVE-2026-71573: Joomla! Core - [20260802] - Improper CORS origin validation in Joomla 4.0.0-5.4.7, 6.0.0-6.1.2

> Attackers can bypass CORS restrictions due to improper origin validation, potentially enabling cross-origin attacks against configured origins.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Aug 2026
- **Updated:** 19 Aug 2026
- **Also known as:** BIT-joomla-2026-71573, GHSA-jm8r-mhmw-h747

## What is CVE-2026-71573?

CVE-2026-71573 is a medium-severity vulnerability in Joomla Joomla\!, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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.

Weakness: CWE-93 (Improper Neutralization of CRLF Sequences)

## Which versions are affected by CVE-2026-71573?

1 open source package ship an affected version, including joomla. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `joomla` | Bitnami | From 4.0.0 | 5.4.8, 6.1.3 |

Products: Joomla Joomla\!.

## How do I fix CVE-2026-71573?

Upgrade joomla to a fixed version for your release line: 5.4.8 or 6.1.3.

## Is CVE-2026-71573 being exploited?

There is no known exploitation of CVE-2026-71573 in the wild and no public exploit code.

## Other vulnerabilities in Joomla Joomla\!

- [CVE-2016-10033](https://insights.sbomify.com/CVE-2016-10033/): PHPMailer Command Injection (critical 9.8, exploited in the wild)
- [CVE-2023-23752](https://insights.sbomify.com/CVE-2023-23752/): Joomla! Improper Access Control (medium 5.3, exploited in the wild)
- [CVE-2026-48902](https://insights.sbomify.com/CVE-2026-48902/): Joomla! Core - [20260518] - Transport encryption downgrade for password and username reset links (critical 9.8)
- [CVE-2025-25226](https://insights.sbomify.com/CVE-2025-25226/): [20250401] - Joomla Framework - SQL injection vulnerability in quoteNameStr method of Database package (critical 9.8)
- [CVE-2022-23795](https://insights.sbomify.com/CVE-2022-23795/): [20220303] - Core - User row are not bound to a authentication mechanism (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-71573 and fix it if it is affected.

What it is: CVE-2026-71573 is a medium-severity vulnerability in Joomla Joomla\!, published on 18 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-71573 in the wild and no public exploit code.

Affected packages and fixed versions:
- joomla (Bitnami): affected from 4.0.0; fixed in 5.4.8, 6.1.3

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-71573/ (Markdown: https://insights.sbomify.com/CVE-2026-71573/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-71573
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-71573
- OSV: https://osv.dev/vulnerability/CVE-2026-71573

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-71573/
Summaries are generated and may contain mistakes; the official description above is the record.