CVE-2026-100824 in Firefox
Summary
by MITRE • 09/29/2026
Privilege escalation in the Places component. This vulnerability was fixed in Firefox ESR 153.4 and Firefox 157.
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Analysis
by VulDB Data Team • 09/30/2026
The identified privilege escalation vulnerability within the Mozilla Places component represents a critical security flaw that allows an attacker to gain elevated permissions beyond their intended scope. The Places subsystem is responsible for managing user history, bookmarks, tags, and other browsing data stored locally on the client machine. By exploiting this specific weakness, a malicious actor can manipulate internal state or memory structures associated with these records, effectively bypassing standard sandbox restrictions that isolate web content from system-level operations. This type of vulnerability is particularly dangerous because it undermines the fundamental isolation model that protects users from arbitrary code execution and unauthorized data access originating from compromised websites or injected scripts.
From a technical perspective, this flaw likely stems from improper validation of input parameters or race conditions during the processing of history entries or bookmark modifications. When an attacker crafts specific requests to interact with the Places API, they can trigger logic errors that result in writing to protected memory regions or executing privileged functions without proper authentication checks. This aligns closely with CWE-269 Improper Privilege Management and CWE-787 Out-of-bounds Write if the escalation involves buffer overflows leading to control flow hijacking. The exploitation typically requires a user to visit a maliciously crafted webpage that leverages JavaScript or other browser technologies to trigger the vulnerable code path within the Places module, making it accessible via standard web-based attack vectors without requiring local file system access initially.
The operational impact of this vulnerability is severe, as successful exploitation can lead to full compromise of the user's browsing session and potentially the underlying operating system depending on how deeply the privilege escalation extends. An attacker could use this foothold to exfiltrate sensitive historical data, inject malicious bookmarks that persist across sessions, or escalate further into executing arbitrary code with higher privileges than those granted to standard web content processes. This compromises not only confidentiality but also integrity and availability of user data. In enterprise environments where Firefox is deployed as the default browser, such vulnerabilities pose significant risks for lateral movement within internal networks if combined with other exploits targeting network-facing services accessible from the compromised endpoint.
Mitigation strategies primarily involve immediate patching to ensure all instances are updated to at least Firefox ESR 153.4 or Firefox 157 where this issue has been resolved. Organizations should enforce automated update policies for browser deployments to minimize exposure windows. Additionally, implementing strict Content Security Policies and disabling unnecessary JavaScript features can reduce the attack surface available to potential exploiters attempting to trigger such vulnerabilities in unpatched environments. Monitoring for anomalous behavior related to history or bookmark manipulation via endpoint detection systems may also provide early warning indicators of exploitation attempts targeting this class of flaws before full privilege escalation occurs.