Security readout for executives and security teams
Plain-English summary
A WordPress plugin called ProSolution WP Client (versions up to 2.0.0) has a critical flaw that lets anyone on the internet upload malicious files to affected sites without logging in. Attackers can use this to take full control of the website, steal data, or use the site to attack visitors. Sites running this plugin should update or disable it immediately.
Executive priority
Treat as an emergency patch. Unauthenticated remote code execution on a public WordPress site can lead to full site takeover, data theft, defacement, SEO poisoning, and pivoting into connected systems. Prioritize inventory, patch or remove the plugin today, and confirm no signs of prior compromise.
Technical view
CVE-2026-6555 is an unauthenticated arbitrary file upload (CWE-434) in the ProSolution WP Client plugin at or below 2.0.0. The upload handler validates extension and MIME type only on the first item in the files array, while iterating and writing every submitted file to a web-accessible directory. This mismatch allows PHP payloads to bypass validation and be written where they can be executed, yielding remote code execution.
Likely exposure
Any WordPress site with ProSolution WP Client installed and network-reachable is exposed. CVSS 9.8 with no authentication or user interaction required. Public plugin source references and a Wordfence advisory increase discoverability. Not listed in CISA KEV as of the source bundle, but the class of bug is routinely weaponized on WordPress.
Exploitation context
No active exploitation is asserted by the cited sources and the CVE is not in KEV. The vulnerability is unauthenticated, network-reachable, and requires no user interaction, which historically drives fast mass-scanning of WordPress plugins after disclosure. Wordfence has published an advisory and the fix commit is public, so defenders should assume exploitation attempts are imminent.
Researcher notes
Root cause is an array-validation mismatch: the handler validates only files[0] for extension and MIME type, then loops through the full array to persist each entry to a web-accessible path. Referenced source lines (UploadHandler.php around 384 and 1345, and class-prosolwpclient-public.php around 998 and 1072) point to the validation and processing loops. Fix landed in changeset 3535622. No CPEs and versions listed only as "0" in the bundle, so confirm the fixed version via the Wordfence advisory before recommending a specific target release.
Mitigation direction
- Update ProSolution WP Client to a version above 2.0.0 or the vendor-fixed release referenced in changeset 3535622.
- If no safe version is available, deactivate and remove the plugin until vendor guidance confirms a fix.
- Block or rate-limit unauthenticated requests to the plugin's upload endpoints at the WAF or reverse proxy.
- Restrict PHP execution in WordPress uploads directories via web server configuration.
- Monitor the uploads directory for newly created PHP or script files and alert on writes.
Validation and detection
- Inventory WordPress sites and confirm whether ProSolution WP Client is installed and its version.
- Compare installed version against the fixed release identified in Wordfence advisory and changeset 3535622.
- Review web server and WordPress logs for POSTs to the plugin's upload handler from unauthenticated clients.
- Scan wp-content/uploads and plugin directories for unexpected PHP files or recent web shells.
- Verify WAF rules block multi-file uploads containing executable extensions to the affected endpoint.
Public sources used
- CVE Program record for CVE-2026-6555
- CVE List V5 JSON entry
- Wordfence Threat Intel advisory
- Plugin source: class-prosolwpclient-public.php line 1072 (trunk)
- Plugin source: UploadHandler.php line 1345 (trunk)
- Plugin source: UploadHandler.php line 384 (trunk)
- Plugin source: class-prosolwpclient-public.php line 998 (trunk)
- WordPress plugin fix changeset 3535622
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-434: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-6555 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9WordfenceVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- Source timelineWordfence
Disclosed
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://www.wordfence.com/threat-intel/vulnerabilities/id/0b870d35-7e10-4fb5-8c3b-2bf299d1f3d5?source=cveCVE reference, Wordfence
- https://plugins.trac.wordpress.org/browser/prosolution-wp-client/trunk/public/class-prosolwpclient-public.php#L1072CVE reference, Wordfence
- https://plugins.trac.wordpress.org/browser/prosolution-wp-client/tags/2.0.0/public/class-prosolwpclient-public.php#L1072CVE reference, Wordfence
- https://plugins.trac.wordpress.org/browser/prosolution-wp-client/trunk/includes/UploadHandler.php#L1345CVE reference, Wordfence
- https://plugins.trac.wordpress.org/browser/prosolution-wp-client/tags/2.0.0/includes/UploadHandler.php#L1345CVE reference, Wordfence
- https://plugins.trac.wordpress.org/changeset/3535622/CVE reference, Wordfence
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Unrestricted Upload of File with Dangerous Type
Unrestricted Upload of File with Dangerous Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.