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Sandbox escape in Mozilla Networking component

IdentifiersCVE-2026-12297CWE-119

CVE-2026-12297 is a sandbox escape vulnerability in the Mozilla Networking component caused by incorrect boundary conditions. Mozilla describes the issue as affecting Firefox and Thunderbird product lines, and fixes were released in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. The available information indicates that the flaw is part of a broader set of sandbox escape issues affecting browser process isolation and sandboxing mechanisms. While the specific vulnerable function is not identified in the provided content, exploitation would allow operations to cross intended sandbox boundaries within the browser architecture.

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ANALYST BRIEF

Impact, mitigation & remediation

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Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can result in a sandbox escape, allowing an attacker to break out of the browser's intended process restrictions. In practical terms, this can increase attacker control beyond the compromised renderer or content context and may enable follow-on privilege escalation, access to resources otherwise blocked by the sandbox, or chaining with a separate memory corruption or code execution vulnerability for broader compromise of the underlying system. The provided content explicitly notes that Mozilla sandbox escape flaws can be chained with browser memory corruption bugs to achieve full browser-to-system compromise.

Mitigation

If you can’t patch tonight, do this now.

No product-specific workaround or temporary mitigation is provided in the supplied advisories. The primary mitigation is prompt patching to the fixed Mozilla versions. Until updates are fully deployed, risk can be reduced by enforcing least privilege, avoiding administrative user contexts, enabling exploit protection and anti-exploitation controls, restricting access to untrusted web content, and using host-based detection/prevention controls, though these measures do not remediate the underlying flaw.

Remediation

Patch, then assume compromise.

Upgrade affected products to fixed versions released by Mozilla. The provided content states that CVE-2026-12297 was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. Debian users should apply the corresponding firefox-esr package update referenced in DSA-6350-1 where applicable.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
MozillaFirefoxapplication
MozillaFirefox Esrapplication

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

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