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WPBruiser EUVDEUVD-2026-53983

| CVE-2026-65556 CRITICAL
Deserialization of Untrusted Data (CWE-502)
2026-08-06 Patchstack GHSA-f7mx-xq66-8fmx
PHP Deserialization Wpbruiser No Captcha Anti Spam
9.8
CVSS 3.1 · Vendor: Patchstack
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Severity by source

Vendor (Patchstack) PRIMARY
9.8 CRITICAL
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
vuln.today AI
9.8 CRITICAL

Unauthenticated network-reachable deserialization (AV:N/PR:N/UI:N/AC:L); worst-case POP chain yields full C/I/A compromise, matching the reported vector.

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

Primary rating from Vendor (Patchstack).

CVSS VectorVendor: Patchstack

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Analysis Generated
Aug 06, 2026 - 15:52 vuln.today
CVE Published
Aug 06, 2026 - 14:27 cve.org
CRITICAL 9.8

DescriptionCVE.org

Unauthenticated PHP Object Injection in WPBruiser {no- Captcha anti-Spam} <= 3.1.43 versions.

Articles & Coverage 1

News Critical PHP Object Injection in WPBruiser WordPress Plugin - CVE-2026-65556 Aug 07, 2026

AnalysisAI

PHP Object Injection in the WPBruiser {no- Captcha anti-Spam} WordPress plugin (versions ≤ 3.1.43) allows remote unauthenticated attackers to inject crafted serialized objects that are deserialized by the plugin, enabling arbitrary object instantiation and, when combined with a suitable POP gadget chain, code execution or data compromise. The flaw carries a CVSS 9.8 (AV:N/AC:L/PR:N/UI:N) and is reported by Patchstack (EUVD-2026-53983). …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Identify WordPress site running WPBruiser ≤3.1.43
Delivery
Craft serialized PHP object payload
Exploit
Submit to plugin input endpoint
Execution
Plugin unserializes untrusted data
Persist
POP gadget magic method fires
Impact
Execute code or tamper with data
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Vulnerability AssessmentAI

Exploitation Exploitation requires that the target site is running WPBruiser {no- Captcha anti-Spam} version 3.1.43 or earlier and that the attacker can reach a plugin input path that passes attacker-controlled data into PHP deserialization - consistent with the unauthenticated network vector (AV:N/PR:N/UI:N), no login or user interaction is needed against a default install. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 3.1 base vector (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H = 9.8) indicates a network-reachable, low-complexity, unauthenticated attack with high impact across confidentiality, integrity, and availability - a strong prioritization signal for an internet-facing WordPress site. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker sends a crafted HTTP request to a public WordPress page or AJAX endpoint handled by WPBruiser, embedding a serialized PHP object string in an input the plugin unserializes. When the plugin deserializes the payload, a POP gadget chain from WordPress core or another installed plugin fires via a magic method, letting the attacker write files, manipulate the database, or execute code - all without authentication. …
Remediation Upgrade to a fixed release above 3.1.43 as soon as the vendor publishes one; the input data does not include a confirmed fixed version, so consult the Patchstack advisory (https://patchstack.com/database/wordpress/plugin/goodbye-captcha/vulnerability/wordpress-wpbruiser-no-captcha-anti-spam-plugin-3-1-43-php-object-injection-vulnerability) for the patched version before deploying. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

Within 24 hours, audit all WordPress installations to identify which are running WPBruiser version 3.1.43 or earlier and assess their criticality and internet exposure. …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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EUVD-2026-53983 vulnerability details – vuln.today
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