CVE-2026-0726 in Nexter Extension Plugin
Summary
by MITRE • 01/20/2026
The Nexter Extension – Site Enhancements Toolkit plugin for WordPress is vulnerable to PHP Object Injection in all versions up to, and including, 4.4.6 via deserialization of untrusted input in the 'nxt_unserialize_replace' function. This makes it possible for unauthenticated attackers to inject a PHP Object. No known POP chain is present in the vulnerable software, which means this vulnerability has no impact unless another plugin or theme containing a POP chain is installed on the site. If a POP chain is present via an additional plugin or theme installed on the target system, it may allow the attacker to perform actions like delete arbitrary files, retrieve sensitive data, or execute code depending on the POP chain present.
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Analysis
by VulDB Data Team • 01/22/2026
The Nexter Extension - Site Enhancements Toolkit plugin for WordPress presents a critical security vulnerability classified as PHP Object Injection in versions up to and including 4.4.6. This vulnerability specifically resides within the 'nxt_unserialize_replace' function where untrusted input undergoes deserialization processes without proper sanitization. The flaw enables unauthenticated attackers to inject malicious PHP objects into the application's execution flow, creating potential entry points for various malicious activities.
The technical nature of this vulnerability aligns with CWE-502 which describes weaknesses related to deserialization of untrusted data. The vulnerability operates through the dangerous practice of allowing external input to control object instantiation within PHP applications. When the plugin processes user-supplied data through the unserialize function, it creates opportunities for attackers to craft malicious serialized objects that, when processed, can trigger unintended behavior within the WordPress environment. This deserialization flaw represents a fundamental security weakness that bypasses normal input validation mechanisms.
The operational impact of this vulnerability remains limited without the presence of additional exploitable components within the target system. The vulnerability requires a second-order attack vector through a POP (Point of Purchase) chain or similar exploit chain that exists within other installed plugins or themes. This dependency means that attackers cannot directly exploit this vulnerability alone but must leverage it as part of a broader attack strategy. The absence of a known POP chain within the vulnerable software itself significantly reduces the immediate threat level, though it does not eliminate the risk entirely.
The potential consequences of exploitation become severe when combined with other vulnerable components within the WordPress installation. Attackers could potentially perform arbitrary file deletion operations, extract sensitive data from the server, or execute arbitrary code depending on the specific POP chain available in the target environment. This vulnerability demonstrates how seemingly isolated security flaws can become critical when combined with other weaknesses in complex software ecosystems. The attack surface expands dramatically when considering that WordPress installations often contain numerous plugins and themes, each potentially introducing additional attack vectors.
Mitigation strategies should focus on immediate plugin updates to versions that address the deserialization vulnerability, along with comprehensive security audits of all installed plugins and themes. Organizations should implement strict input validation measures and consider implementing web application firewalls to monitor for suspicious deserialization patterns. The principle of least privilege should be enforced through proper file permissions and restricted server access. Additionally, security monitoring should include detection of unusual file operations and unauthorized data access patterns that might indicate exploitation attempts. Regular security assessments and vulnerability scanning should be conducted to identify potential POP chains or other exploitable components that could amplify the impact of this vulnerability. The ATT&CK framework's T1059.007 technique for command and scripting interpreter indicates that such vulnerabilities could enable attackers to execute arbitrary code, while T1566 covers social engineering aspects that might be used to deliver malicious payloads through compromised plugins.