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One User Avatar EUVDEUVD-2026-67408

| CVE-2026-18983 HIGH
Unrestricted Upload of File with Dangerous Type (CWE-434)
2026-08-28 Wordfence GHSA-p2qh-mgvf-5q7f
7.5
CVSS 3.1 · Vendor: Wordfence
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Authenticate as subscriber
  2. Delivery
    Request or obtain avatar upload permission
  3. Exploit
    Upload crafted DXFP file with executable payload
  4. Execution
    Bypass MIME validation via attacker-controlled Content-Type
  5. Persist
    File persists on server after failed cleanup
  6. Impact
    Retrieve file URL to trigger server-side execution

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A06:2025 - Insecure Design
ASVS 5.0
V5 - File Handling File type validation, storage isolation
MITRE ATT&CK

2 techniques across 2 tactics: Command and Control, Persistence

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Two concrete prerequisites must both be satisfied: (1) the attacker must hold a valid WordPress account at subscriber level or above - unauthenticated exploitation is not possible given PR:L in the CVSS vector; (2) a site administrator must have explicitly enabled the non-default setting that allows subscribers to upload avatars - without this grant, the vulnerable upload code path is unreachable by low-privileged users. What limits exploitation: the admin configuration requirement is the dominant gating factor; default WordPress installations do not grant subscribers avatar upload rights. Additionally, PHP and SVG file types are explicitly rejected by the plugin, narrowing the usable payload formats to types like DXFP that escape the blocklist. Sites with closed user registration face negligible risk unless an insider threat is considered.

Impact

The supplied CVSS 3.1 vector (AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H) scores 7.5, which accurately reflects the dual conditions required: subscriber-level authentication (PR:L) and a non-default administrator decision to enable subscriber avatar uploads (AC:H). Without that administrative grant, exploitation is impossible regardless of CVSS impact metrics. No EPSS score was provided; no CISA KEV listing is present; no public POC is known - all of which temper urgency despite the high theoretical impact. Real-world risk is meaningfully lower than a naïve CVSS read suggests: the combination of needing a registered account and an explicit admin misconfiguration creates a significant barrier. However, multi-tenant WordPress environments (shared hosting, SaaS-style site builders) where subscriber registration is open and avatar permissions are loosely managed face material exposure. The severity escalates sharply if those two conditions are met, since successful exploitation yields full server-side RCE.

Exploit ScenarioDerived

An attacker registers or compromises a subscriber-level account on a WordPress site where the administrator has enabled avatar uploads for subscribers. The attacker submits a crafted DXFP file with executable server-side content via the avatar upload endpoint, supplying a benign Content-Type header to bypass MIME validation; the file is written to the uploads directory and retained even if the post-write check flags it. The attacker then requests the file's URL directly, triggering server-side execution and achieving RCE under the web server's process identity.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Aug 28, 2026

Remote code execution via unrestricted file upload in the One User Avatar WordPress plugin (all versions ≤ 2.5.4) is enabled by a flawed avatar upload handler that accepts DXFP files - bypassing only PHP and SVG blocks - while trusting the attacker-controlled client-supplied Content-Type header instead of a server-derived MIME type, and retaining uploaded files that fail post-write validation. Exploitation requires subscriber-level WordPress credentials and a non-default administrative decision to grant subscribers avatar upload capability. No public exploit has been identified at time of analysis; no EPSS data was provided.

RemediationAI

Upstream fix available via plugin changeset 3659509, which transitions the codebase from the 2.5.4 tag to the 2.5.5 tag (see https://plugins.trac.wordpress.org/changeset?old_path=%2Fone-user-avatar/tags/2.5.4&new_path=%2Fone-user-avatar/tags/2.5.5); the patched released version is inferred as 2.5.5 but not independently confirmed as a WordPress.org repository release at time of analysis - verify availability in the plugin directory before deploying. Until patching is confirmed and applied, the single most effective compensating control is revoking subscriber-level avatar upload permissions in WordPress admin settings, as this eliminates the exploitation path entirely without functional impact to administrator or editor users. Additionally, organizations should audit current uploaded avatar files for unexpected DXFP or other non-image extensions, restrict direct web access to the WordPress uploads directory for non-image MIME types via server configuration (e.g., an Apache FilesMatch or nginx location block), and review whether open subscriber registration is necessary.

Affected VersionsENISA

One User Avatar | User Profile Picture 0 ≤2.5.4

Affected Packages

euvd one_user_avatar_user_profile_picture no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

The vulnerability resides in the wpua_action_process_option_update function within class-wp-user-avatar.php (lines ~45, 546-549 per Wordfence Trac references), which invokes WordPress core's wp_handle_upload() without supplying a MIME allow-list. CWE-434 (Unrestricted Upload of File with Dangerous Type) describes the root cause: the plugin delegates MIME determination to the client's Content-Type header rather than performing server-side magic-byte or extension-based validation. Because PHP and SVG extensions are explicitly blocked but the DXFP extension is not, and because files that fail the post-write check are not removed, an attacker can stage an executable payload on the server's filesystem. Affected product is identified via CPE cpe:2.3:a:onedesigns:one_user_avatar_|_user_profile_picture:*:*:*:*:*:*:*:*, covering all releases through 2.5.4.

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Severity by source

Vendor (Wordfence) PRIMARY 7.5 HIGH
AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
vuln.today AI 7.5 HIGH

AC:H reflects the non-default admin configuration prerequisite; PR:L reflects required subscriber authentication; full C/I/A impact reflects RCE potential on the vulnerable WordPress host.

3.1 AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from Vendor (Wordfence).

CVSS VectorVendor: Wordfence

Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

The One User Avatar | User Profile Picture plugin for WordPress is vulnerable to Stored Cross-Site Scripting in all versions up to, and including, 2.5.4 via the wpua_action_process_option_update function. This is due to insufficient file type validation in wp_handle_upload() called without a MIME allow-list, with post-write validation relying on the attacker-controlled client-supplied Content-Type header rather than a server-derived type, and no cleanup of files that fail the check. This makes it possible for authenticated attackers, with subscriber-level access and above, to upload files that may be executable, which makes remote code execution possible. in order to exploit this vulnerability an admin has to give subscribers permission to upload avatars. While PHP files and svg files are rejected, dxfp files are accepted.

Executive ViewAI

Why It Matters

The One User Avatar WordPress plugin (versions ≤ 2.5.4) contains a remote code execution vulnerability affecting any WordPress site where the plugin is active and subscribers are permitted to upload avatars. An attacker with subscriber credentials could upload and execute malicious code on the server, compromising the site, stealing data, or establishing persistent access to your WordPress infrastructure.

Business Impact: High
Compensating Controls

Disable the One User Avatar plugin immediately, or restrict the subscriber user role by removing avatar upload permissions. Implement server-level file upload restrictions to reject executable file types. Monitor WordPress file directories and audit logs for suspicious uploads. Keep WordPress core and all remaining plugins patched to current versions.

Threat Intelligence Overview

EPSS Score
0.5%
Top 59% exploitable
Prevalence
Medium
WordPress avatar plugin with moderate install base, not ubiquitous
Social Media
1
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.5%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
High
Technical Impact
Total

Priority Score

39
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +38
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Malicious file upload attacks exploit insufficient validation when web applications accept user-provided files.

Remote Code Execution represents the critical moment when an attacker successfully runs arbitrary code on a target system without physical access.

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