EUVD-2026-84308
GHSA-4r25-cpgx-8q2p
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain
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AccessAuthenticate as Subscriber-level user
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DeliveryCraft POST to admin-ajax.php
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ExploitInvoke wp_ajax_pl-plugin-deactivation action
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ExecutionBypass absent capability/nonce checks
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ImpactDeactivate ThumbPress plugin
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V8 - Authorization Authorization checks on every request
MITRE ATT&CK
1 technique across 1 tactic: Privilege Escalation The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Exploitation Conditions | Requires an authenticated account with at least Subscriber-level access on a site running ThumbPress <=6.2.1, and the ability to reach /wp-admin/admin-ajax.php with the wp_ajax_pl-plugin-deactivation action. No user interaction, no admin privileges, and no special non-default configuration are needed beyond the plugin being installed and active. The limiting factor is authentication: sites that do not permit low-privilege user registration substantially reduce exposure. Impact is bounded to deactivating the plugin - no data access, code execution, or persistence is possible through this flaw. |
| Impact | This is a genuinely low-priority issue despite the network attack vector. The CVSS 4.3 (AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N) correctly caps impact at Integrity:Low with no confidentiality or availability loss, because the only outcome is deactivating one plugin. PR:L confirms a valid Subscriber-level (or higher) account is required, so this is not an unauthenticated internet-facing bug. No EPSS score, no CISA KEV listing, and no public exploit code were provided in the intelligence - so this falls into 'no public exploit identified at time of analysis.' The realistic blast radius is limited: an authenticated low-privilege user can turn off ThumbPress, degrading image optimization/thumbnail features, but cannot read data, escalate privileges, or execute code through this flaw alone. No signals conflict here; all sources (Wordfence CVSS, CWE-862 Missing Authorization, description) agree the severity is modest. This is a 'medium-CVSS-but-low-real-risk' item best patched in routine maintenance rather than emergency response. |
| Exploit ScenarioDerived | A registered low-privilege user (e.g., a Subscriber on a site allowing open registration) sends a crafted POST request to /wp-admin/admin-ajax.php invoking the pl-plugin-deactivation action. Because send_deactivation_survey() performs no capability check and no nonce verification, the request succeeds and ThumbPress is deactivated, disrupting image compression/thumbnail handling. No public proof-of-concept was referenced in the provided intelligence. |
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Alert meAnalysisAIv1 – Sep 22, 2026
Any authenticated WordPress user holding only Subscriber-level access can remotely deactivate the ThumbPress plugin on versions 6.2.1 and earlier, because the send_deactivation_survey() handler registered to the wp_ajax_pl-plugin-deactivation action performs no capability check and no nonce verification. The impact is deliberately narrow - a low-privilege account can only turn the plugin off, with no path to data disclosure, code execution, or persistence - which aligns with the assessed CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N score of 4.3. No public exploit code or confirmed active exploitation was identified at time of analysis, and exposure is limited to sites that actually allow low-privilege user registration; the upstream code change is visible in the public Trac changeset referenced by the advisory.
RemediationAI
Update ThumbPress past 6.2.1 as soon as a release containing Trac changeset 3560270 is available - upstream fix available (changeset/commit); released patched version not independently confirmed, so verify the installed version against the vendor changelog before assuming you are covered. If immediate updating is not possible, the most effective compensating control is to close the authentication prerequisite: disable open user registration and audit for any Subscriber-or-lower accounts that should not exist, since the attack requires a valid low-privilege login with no default configuration change otherwise; the trade-off is loss of self-service signups and, on membership or e-commerce sites, disruption to legitimate low-privilege users. A WAF rule that blocks POST requests to /wp-admin/admin-ajax.php carrying action=pl-plugin-deactivation is a targeted interim control, but it must be tuned because other legitimate admin-ajax traffic shares the same endpoint. Administrators who neither need the plugin nor can patch quickly can simply deactivate and delete ThumbPress, accepting the loss of its image-compression, WebP/AVIF, lazy-loading and hotlinking features; long-term, restrict or rate-limit access to wp-admin/admin-ajax.php for low-privilege roles, understanding that some front-end AJAX functionality may break. Because the handler also lacks nonce verification, treat unexpected ThumbPress deactivations as a signal to rotate credentials and review user accounts for unauthorized additions.
Affected VersionsENISA
Affected Packages
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 flaw is a classic CWE-862 (Missing Authorization) defect in the WordPress plugin ecosystem. ThumbPress bundles a vendor library at vendor/pluggable/marketing/src/Deactivator.php, which registers an AJAX handler through add_action('wp_ajax_pl-plugin-deactivation', ...). Because the handler is registered on the authenticated wp_ajax_ hook, WordPress authenticates the request but performs no further privilege check, and the function itself omits both a current_user_can() capability test and a check_ajax_referer()/wp_verify_nonce() validation. Any logged-in user - Subscriber role included - can therefore reach /wp-admin/admin-ajax.php with action=pl-plugin-deactivation and a posted survey payload and cause the plugin to be deactivated. Notably, the CPE identifier points to codexpert's ThumbPress, while the referenced Trac file paths are under the plugin slug image-sizes, reflecting the plugin's earlier name; the vulnerable Deactivator class is present in the trunk branch and in the tagged 5.8.37 tree, showing the code shipped long before the 6.2.x releases. The documented fix is Trac changeset 3560270.
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- Exploit and PoC references, threat intelligence from 22 sources
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Severity by source
AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N
Remote AJAX endpoint (AV:N/AC:L), requires a low-privilege authenticated account (PR:L), no UI; only site-state change (plugin deactivation) gives I:L with no C or A impact.
Primary rating from Vendor (Wordfence).
CVSS VectorVendor: Wordfence
DescriptionCVE.org
The ThumbPress plugin for WordPress is vulnerable to unauthorized access in versions up to and including 6.2.1. This is due to missing capability checks and nonce verification in the send_deactivation_survey() function registered via the wp_ajax_pl-plugin-deactivation AJAX action. This makes it possible for authenticated attackers, with Subscriber-level access and above, to deactivate the ThumbPress plugin on the affected site by sending a crafted POST request to admin-ajax.
Threat Intelligence Overview
NVD
CVE.org
EPSS
Vulnrichment
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.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.
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