CVE-2026-77871 Details
Description
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.
A stored cross-site scripting vulnerability has been identified in the Post Snippets - Custom WordPress Code Snippets Customizer plugin, affecting all versions through 4.2.4. The issue arises from inadequate input sanitization and output escaping, allowing authenticated attackers with contributor-level access or higher to inject arbitrary scripts into pages. These scripts execute when a user accesses the affected page. Entity-encoded payloads, such as <script> tags, can bypass WordPress's wp_kses_post sanitization because the kses function does not decode HTML entities. Instead, the entities are converted back into executable HTML at render time by the plugin's shortcode filter, requiring snippet shortcodes to be enabled.
Users are advised to update the Post Snippets - Custom WordPress Code Snippets Customizer plugin to version 4.2.5 or a newer patched version.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Oct 28, 2026CISA-ADP
Assessed Oct 29, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-79 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Post Snippets | <= 4.2.4 (semver) |
CPE
Remediation
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Change History
2 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Oct 29, 2026 | CVE Modified | CISA-ADP |
| Oct 28, 2026 | New CVE Received | [email protected] |