CVE-2026-6403

CVE-2026-6403 is a high-severity vulnerability with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-22.

Key facts

• Severity: High (CVSS 3.x base score 7.5)
• EPSS exploit prediction: 1% (53rd percentile)
• Actively exploited: Not listed in CISA KEV
• EU (EUVD) id: EUVD-2026-30517
• Weakness: CWE-22
• Published: 2026-05-15
• Last modified: 2026-06-17

Description

The Quick Playground plugin for WordPress is vulnerable to Path Traversal in versions up to and including 1.3.3. This is due to insufficient path validation in the qckply_zip_theme() function, which appends a user-controlled 'stylesheet' parameter directly to the theme root directory path without sanitizing directory traversal sequences. This makes it possible for unauthenticated attackers to trigger the creation of a ZIP archive containing arbitrary files from the server's filesystem — including wp-config.

Frequently asked questions

What is CVE-2026-6403?

The Quick Playground plugin for WordPress is vulnerable to Path Traversal in versions up to and including 1.3.3. This is due to insufficient path validation in the qckply_zip_theme() function, which appends a user-controlled 'stylesheet' parameter directly to the theme root directory path without sanitizing directory traversal sequences. This makes it possible for unauthenticated attackers to trigger the creation of a ZIP archive containing arbitrary files from the server's filesystem — including wp-config.

How severe is CVE-2026-6403?

CVE-2026-6403 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-6403 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-6403?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-6403 have an EU (EUVD) identifier?

Yes. CVE-2026-6403 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30517.

When was CVE-2026-6403 published?

CVE-2026-6403 was published on 2026-05-15 and last updated on 2026-06-17.

References

• https://plugins.trac.wordpress.org/browser/quick-playground/tags/1.3.1/api.php#L62
• https://plugins.trac.wordpress.org/browser/quick-playground/tags/1.3.1/api.php#L631
• https://plugins.trac.wordpress.org/browser/quick-playground/tags/1.3.1/utility.php#L162
• https://plugins.trac.wordpress.org/browser/quick-playground/tags/1.3.1/utility.php#L248
• https://plugins.trac.wordpress.org/browser/quick-playground/trunk/api.php#L62
• https://plugins.trac.wordpress.org/browser/quick-playground/trunk/api.php#L631
• https://plugins.trac.wordpress.org/browser/quick-playground/trunk/utility.php#L162
• https://plugins.trac.wordpress.org/browser/quick-playground/trunk/utility.php#L248
• https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3514238%40quick-playground&new=3514238%40quick-playground&sfp_email=&sfph_mail=
• https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=3523317%40quick-playground&new=3523317%40quick-playground&sfp_email=&sfph_mail=
• https://www.wordfence.com/threat-intel/vulnerabilities/id/a39dccb6-b635-44af-b0e0-c3010b719773?source=cve

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