WordPress Kirki Plugin PHP Object Injection Escalation

The Kirki plugin for WordPress is vulnerable to Privilege Escalation via PHP Object Injection in all versions up to, and including, 6.2.5 via deserialization of untrusted input through the 'get-single-symbol' branch of the kirki_post_apis() AJAX dispatcher due to a missing capability check. This makes it possible for authenticated attackers, with Subscriber-level access and above, to inject a PHP Object. The additional presence of a POP chain allows attackers to overwrite an administrator's password and gain administrative access.

Casky was already ahead

This CVE exploits attack patterns that Casky's 447matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

The Kirki plugin for WordPress contains a critical privilege escalation vulnerability (CVE-2026-75891, CVSS 8.8) stemming from unsafe deserialization of untrusted input in the 'get-single-symbol' AJAX dispatcher. The vulnerability exploits CWE-502 (Deserialization of Untrusted Data) combined with a missing capability check, allowing authenticated users with Subscriber-level permissions to inject malicious PHP objects. When a suitable PHP Object Chain (POP chain) exists in the WordPress environment, attackers can escalate privileges to administrator level and compromise site integrity. This affects all Kirki versions through 6.2.5 and poses a significant risk to WordPress installations using this popular customization plugin, as the attack requires only low-level authentication—a common access vector in multi-user WordPress environments.

Casky's 447 mapped skills detect this attack through Claude AI's analysis of three critical MITRE ATT&CK techniques: Initial Access (TA0001) identifies the authenticated entry point via Subscriber accounts, Execution (TA0002) monitors for suspicious PHP object instantiation and method invocation patterns in AJAX handlers, and Privilege Escalation (TA0043) tracks the escalation chain from Subscriber to Administrator roles. Practitioners using Casky would observe findings highlighting unsafe unserialize() calls on user-controlled input in the kirki_post_apis() function, missing is_admin() or current_user_can() capability checks before deserialization, and anomalous POP chain gadget utilization that attempts to modify user role metadata. Extended reasoning enables detection of the logical flow connecting low-privilege authentication, untrusted input handling, and privilege boundary violations—patterns that traditional static analysis might miss without understanding the full attack context.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

447 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-75891.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

Run

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

MITRE ATT&CK Techniques

TA0001 TA0043 TA0002

Investigate the attack patterns behind CVE-2026-75891

Casky has 447 skills that investigate the attack patterns behind CVE-2026-75891. Run one and get CVSS-scored findings in 3 minutes.

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