Stored cross-site scripting in Post Grid Gutenberg Blocks plugin
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Cross-site scripting
- Confidentiality · integrity · availability
- Low · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-79.
Summary
The Post Grid Gutenberg Blocks (PostX) plugin for WordPress, through 5.1.0, does not sufficiently sanitize or escape the display_name user field, which is a stored cross-site scripting flaw (CWE-79). WordPress core leaves double quotes unencoded in display names, so a stored name can break out of an HTML attribute. An unauthenticated attacker can inject arbitrary web scripts that execute when a user accesses an affected page.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
The Post Grid Gutenberg Blocks – PostX plugin for WordPress is vulnerable to Stored Cross-Site Scripting via display_name User Field in all versions up to, and including, 5.1.0 due to insufficient input sanitization and output escaping. This makes it possible for unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. WordPress core's pre_user_display_name filter encodes &, <, and > but leaves double-quotes intact (ENT_NOQUOTES), allowing a Subscriber-level user to store a double-quote in their display_name via /wp-admin/profile.php that subsequently breaks out of the alt="" attribute at Archive_Title.php:144.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
The sources list no fixed version for Post Grid Gutenberg Blocks (PostX).
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Timeline
- 2026-10-10 Threatist record created from CVE-2026-96840
- 2026-10-10 Alias added: GHSA-8pf3-qx3w-w4jg
- 2026-10-11 CISA SSVC decision points changed
- 2026-10-11 Priority changed: MEDIUM → LOW
References
Other 5
- https://www.wordfence.com/threat-intel/vulnerabilities/id/39472e87-174c-4abf-bc83-fed0939440af?source=cve
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.41/addons/builder/blocks/Archive_Title.php#L144
- https://plugins.trac.wordpress.org/browser/ultimate-post/tags/5.0.41/addons/builder/blocks/Archive_Title.php#L98
- https://wordpress.org/plugins/ultimate-post/
- https://plugins.trac.wordpress.org/changeset/3727209/ultimate-post/trunk/addons/builder/blocks/Archive_Title.php
More wpxpo vulnerabilities
- TI-2024-09942 PostX <= 4.1.16 - Missing Authorization to Arbitrary Plugin Installation/Activation CVSS 3.1HIGH 8.8
- TI-2024-04008 PostX < 4.1.0 - Contributor+ Stored XSS CVSS 3.1MEDIUM 6.8
- TI-2023-03707 PostX - Gutenberg Post Grid Blocks < 3.0.6 - Reflected Cross-Site Scripting CVSS 3.1MEDIUM 6.1
- TI-2024-20266 WordPress WholesaleX plugin <= 1.3.2 - Unauthenticated Privilege Escalation vulnerability CVSS 3.1CRITICAL 9.8
- TI-2024-19970 WordPress WholesaleX plugin <= 1.3.2 - Unauthenticated PHP Object Injection vulnerability CVSS 3.1CRITICAL 10.0
- TI-2024-15553 WordPress ProductX – Gutenberg WooCommerce Blocks Plugin <= 3.1.4 is vulnerable to PHP Object Injection CVSS 3.1CRITICAL 9.8
Sources
- CVE-2026-96840 · CVE Program
- CVE-2026-96840 · NVD
- FIRST EPSS
- GHSA-8pf3-qx3w-w4jg · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences