CVE-2026-6399

CVE-2026-6399 is a medium-severity vulnerability with a CVSS 3.x base score of 4.4. 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-79.

Key facts

Description

The General Options plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to and including 1.1.0. This is due to the use of sanitize_text_field() for output escaping in the Contact Number (ad_contact_number) field — a function that strips HTML tags but does not encode double-quote characters to their HTML entity equivalent ("). When the stored value is echoed inside a double-quoted HTML attribute (value="..."), an attacker-supplied double-quote character breaks out of the attribute context. Even with WordPress's wp_magic_quotes mechanism (which prefixes quotes with a backslash), the resulting \" sequence is NOT treated as an escaped quote by HTML parsers — the backslash is rendered as a literal character and the bare double-quote still closes the attribute. This makes it possible for authenticated attackers with Administrator-level access and above to inject arbitrary web scripts in the admin settings page that will execute whenever any administrator visits the General Options settings page.

Frequently asked questions

What is CVE-2026-6399?
The General Options plugin for WordPress is vulnerable to Stored Cross-Site Scripting in versions up to and including 1.1.0. This is due to the use of sanitize_text_field() for output escaping in the Contact Number (ad_contact_number) field — a function that strips HTML tags but does not encode double-quote characters to their HTML entity equivalent ("). When the stored value is echoed inside a double-quoted HTML attribute (value="..."), an attacker-supplied double-quote character breaks out of the attribute context. Even with WordPress's wp_magic_quotes mechanism (which prefixes quotes with a backslash), the resulting \" sequence is NOT treated as an escaped quote by HTML parsers — the backslash is rendered as a literal character and the bare double-quote still closes the attribute. This makes it possible for authenticated attackers with Administrator-level access and above to inject arbitrary web scripts in the admin settings page that will execute whenever any administrator visits the General Options settings page.
How severe is CVE-2026-6399?
CVE-2026-6399 has a CVSS 3.x base score of 4.4, rated medium severity. It is exploitable over network with high attack complexity, requires high privileges and no user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2026-6399 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (14th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-6399?
Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-6399 have an EU (EUVD) identifier?
Yes. CVE-2026-6399 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-31040.
When was CVE-2026-6399 published?
CVE-2026-6399 was published on 2026-05-20 and last updated on 2026-06-17.

References

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