CVE-2026-117893 in Firefox
Summary
by MITRE • 10/27/2026
Incorrect boundary conditions in the Security: PSM component. This vulnerability was fixed in Firefox 159, Firefox ESR 115.44, and Firefox ESR 153.6.
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Analysis
by VulDB Data Team • 10/27/2026
The identified security flaw resides within the Privileged Session Manager or related session handling components of the Mozilla Firefox browser ecosystem, specifically categorized under incorrect boundary conditions. This type of vulnerability typically arises when software fails to properly validate input data against expected limits, allowing an attacker to manipulate internal state variables by providing values that exceed predefined thresholds or fall outside acceptable ranges. In the context of a privileged component such as PSM, which often manages cryptographic contexts and secure session states, improper boundary checks can lead to memory corruption, logic errors, or unauthorized access to sensitive security parameters. The root cause is generally a failure in input validation routines where integer overflows, array index out-of-bounds accesses, or logical state transitions are not adequately guarded against maliciously crafted inputs.
From an operational perspective, this vulnerability poses significant risks to the integrity and confidentiality of user sessions. If exploited successfully, it could allow a remote attacker to bypass security controls, potentially leading to session hijacking, privilege escalation within the browser process sandbox, or arbitrary code execution depending on how the boundary condition is leveraged in conjunction with other memory management flaws. Such exploits often target the trust boundaries between different parts of the browser architecture, exploiting weaknesses where data flows from untrusted sources into privileged contexts without sufficient sanitization. The impact extends beyond individual user compromise to potentially undermining the broader security model that relies on strict isolation and correct state management within the browser engine.
This vulnerability aligns with common weakness enumerations such as CWE-190 Integer Overflow or Wraparound, CWE-787 Out-of-bounds Write, or CWE-20 Improper Input Validation, depending on the specific implementation details of the boundary check failure. In terms of attack vectors and techniques, it may relate to ATT&CK tactics involving initial access or privilege escalation through exploitation of application logic flaws. Attackers might craft specially designed web pages or malicious content that triggers these incorrect boundary conditions during session initialization or state updates, leveraging timing differences or race conditions if applicable to further destabilize the component's internal consistency.
To mitigate this risk, users must ensure they are running a patched version of Firefox, specifically version 159 for standard releases and versions 115.44 and 153.6 for Extended Support Release channels. These updates contain code changes that enforce stricter validation checks on inputs processed by the PSM component, ensuring that boundary conditions are correctly evaluated before any state modifications occur. Additionally, organizations should implement strict content security policies to limit the execution of untrusted scripts and employ browser hardening techniques such as disabling unnecessary plugins or features that could expand the attack surface. Regular monitoring for vendor updates and automated patch management systems are essential to maintain a secure posture against evolving threats targeting browser internals.