DOM Workers Component Privilege Escalation in Firefox

Privilege escalation in the DOM: Workers component. This vulnerability was fixed in Firefox 153 and Thunderbird 153.

Casky was already ahead

This CVE exploits attack patterns that Casky's 224matched 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

CVE-2026-16365 represents a critical privilege escalation vulnerability in Firefox and Thunderbird's DOM Workers component, scoring 9.8 on the CVSS scale. This vulnerability allows attackers to elevate their privileges within the browser's worker context, potentially breaking the isolation boundaries that protect the main thread from untrusted code. DOM Workers are a fundamental JavaScript feature used for background processing, and their compromise affects any user running vulnerable versions of Firefox (pre-153) or Thunderbird (pre-153). The vulnerability stems from improper access control (CWE-284) and incorrect privilege assignment (CWE-269), making it particularly dangerous as it enables attackers to bypass browser security sandboxing—a core defense mechanism protecting end users from malicious web content.

Casky's 224 mapped skills identify this attack pattern through Claude's extended reasoning capabilities applied to MITRE ATT&CK technique TA0004 (Privilege Escalation). Practitioners using Casky would observe detection patterns aligned with browser sandbox escape attempts, unauthorized capability elevation within worker threads, and anomalous inter-process communication between worker contexts and privileged browser components. The platform's skill set would flag suspicious DOM manipulation patterns, unexpected permission acquisitions, and behavioral indicators suggesting an attacker leveraging worker isolation bypass techniques. Security teams would see findings highlighting the transition from user-level code execution to higher-privileged execution contexts, combined with detection of exploitation artifacts specific to worker component memory access or capability delegation vulnerabilities—enabling faster incident response and threat hunting focused on browser-based privilege escalation attempts.

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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 →

224 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-16365.

abusing-dpapi-for-credential-access

red teaming · high

Run

abusing-shadow-credentials-for-privesc

red teaming · high

Run

Access with Stolen Session Cookie

penetration testing · medium

Run

MITRE ATT&CK Techniques

TA0004

Investigate the attack patterns behind CVE-2026-16365

Casky has 224 skills that investigate the attack patterns behind CVE-2026-16365. Run one and get CVSS-scored findings in 3 minutes.

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