Firefox 152 Sandbox Escape in Process Sandboxing Component
CVE-2026-12296 Published on June 16, 2026
Sandbox escape in the Security: Process Sandboxing component
Sandbox escape in the Security: Process Sandboxing component. This vulnerability was fixed in Firefox 152, Firefox ESR 140.12, Thunderbird 152, and Thunderbird 140.12.
Vulnerability Analysis
CVE-2026-12296 is exploitable with network access, requires user interaction. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to be very high.
Weakness Types
Protection Mechanism Failure
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. This weakness covers three distinct situations. A "missing" protection mechanism occurs when the application does not define any mechanism against a certain class of attack. An "insufficient" protection mechanism might provide some defenses - for example, against the most common attacks - but it does not protect against everything that is intended. Finally, an "ignored" mechanism occurs when a mechanism is available and in active use within the product, but the developer has not applied it in some code path.
What is a File descriptor leak Vulnerability?
A process does not close sensitive file descriptors before invoking a child process, which allows the child to perform unauthorized I/O operations using those descriptors. When a new process is forked or executed, the child process inherits any open file descriptors. When the child process has fewer privileges than the parent process, this might introduce a vulnerability if the child process can access the file descriptor but does not have the privileges to access the associated file.
CVE-2026-12296 has been classified to as a File descriptor leak vulnerability or weakness.
Products Associated with CVE-2026-12296
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Affected Versions
Mozilla Firefox:- Version 140.12, <= 140.* is unaffected.
- Version 152, <= * is unaffected.
- Version 140.12, <= 140.* is unaffected.
- Version 152, <= * is unaffected.
- Version 0:140.12.0-1.el10_2 and below * is unaffected.
- Version 0:140.12.0-1.el10_2 and below * is unaffected.
- Version 0:140.12.0-1.el10_0 and below * is unaffected.
- Version 0:140.12.0-1.el10_0 and below * is unaffected.
- Version 0:140.12.0-1.el7_9 and below * is unaffected.
- Version 0:140.12.0-1.el8_10 and below * is unaffected.
- Version 0:140.12.0-1.el8_10 and below * is unaffected.
- Version 0:140.12.0-1.el8_4 and below * is unaffected.
- Version 0:140.12.0-1.el8_4 and below * is unaffected.
- Version 0:140.12.0-1.el8_4 and below * is unaffected.
- Version 0:140.12.0-1.el8_4 and below * is unaffected.
- Version 0:140.12.0-1.el8_6 and below * is unaffected.
- Version 0:140.12.0-1.el8_6 and below * is unaffected.
- Version 0:140.12.0-1.el8_6 and below * is unaffected.
- Version 0:140.12.0-1.el8_6 and below * is unaffected.
- Version 0:140.12.0-1.el8_8 and below * is unaffected.
- Version 0:140.12.0-1.el8_8 and below * is unaffected.
- Version 0:140.12.0-1.el8_8 and below * is unaffected.
- Version 0:140.12.0-1.el8_8 and below * is unaffected.
- Version 0:140.12.0-1.el9_8 and below * is unaffected.
- Version 0:140.12.0-1.el9_8 and below * is unaffected.
- Version 0:140.12.0-1.el9_2 and below * is unaffected.
- Version 0:140.12.0-1.el9_4 and below * is unaffected.
- Version 0:140.12.0-1.el9_4 and below * is unaffected.
- Version 0:140.12.0-1.el9_6 and below * is unaffected.
- Version 0:140.12.0-1.el9_6 and below * is unaffected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.