CVE-2026-77871: Post Snippets stored cross-site scripting (XSS) vulnerability
medium 6.4 plugin closed published 2026-10-28 · updated 2026-10-29
- Affected versions
- 4.2.4 and older
- Fixed in
- unknown
- Severity
- Medium · CVSS 6.4
- Active installs
- closed
- Type
- Stored cross-site scripting (XSS)
What an attacker needs
- Access: A logged-in account with Contributor-level access or higher.
CVSS vector (score by Wordfence): CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
What to do now
- Replace Post Snippets. A closed plugin gets no updates through WordPress, so this hole stays open.
- Deactivate and delete it once you have a replacement (Plugins → Deactivate → Delete). Deactivating alone leaves its files on the server.
- Not sure which version you run? Check your version against every known Post Snippets issue.
- If you ran an affected version and something looks off (new admin users, spam pages, redirects), run the free scan below.
The advisory
The Post Snippets – Custom WordPress Code Snippets Customizer plugin for WordPress is vulnerable to Stored Cross-Site Scripting via Shortcode Attributes in all versions up to, and including, 4.2.4 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. Entity-encoded payloads such as <script>...</script> survive WordPress's wp_kses_post on-save sanitization because kses does not decode HTML entities, and are only converted back into executable HTML tags at render time by the plugin's own shortcode filter. This requires snippet shortcodes to be enabled.
References
- NVD CVE-2026-77871 nvd.nist.gov
- Wordfence advisory www.wordfence.com
- Code change (fix) plugins.trac.wordpress.org
- Plugin source plugins.trac.wordpress.org
Related
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Where this data comes from
- CVE record, score and references: NIST National Vulnerability Database (NVD), checked 2026-11-04. This product uses data from the NVD API but is not endorsed or certified by the NVD.
- Versions and install counts: wordpress.org/plugins/post-snippets (Plugins API), fetched 2026-11-04.
- The summary, “what an attacker needs” and “what to do” sections are our plain-English reading of the record and the plugin's release history; the quoted description is the record's own text. Spot an error? Email Daniel.