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Sandbox escape in Firefox DOM Navigation component

IdentifiersCVE-2026-12295CWE-693

CVE-2026-12295 is a sandbox escape vulnerability in the DOM Navigation component of Mozilla Firefox and related Mozilla products. The provided content identifies the issue as a sandbox escape in the DOM: Navigation component and states it was fixed in Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, and Thunderbird 140.12. While the specific vulnerable function or code path is not provided, the flaw affects browser sandboxing boundaries and could be triggered through crafted web content as part of the broader set of Mozilla vulnerabilities addressed in MFSA 2026-57 and related advisories.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

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

Successful exploitation could allow an attacker to escape the browser sandbox. In the provided context, sandbox escape flaws are significant because they can be chained with separate memory corruption or code execution vulnerabilities to move from compromise of a browser process to compromise of the underlying operating system or user context. The content also notes that Mozilla advisories for this release family include potential outcomes such as privilege escalation, information disclosure, and arbitrary code execution when vulnerabilities are chained.

Mitigation

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

No vendor-provided workaround or temporary mitigation is described in the supplied content. The primary mitigation is prompt patching. Until updates are fully deployed, reduce exposure by enforcing least privilege, avoiding administrative browsing sessions, enabling exploit protection controls, restricting access to untrusted web content, and using host-based detection/prevention controls, as reflected in downstream advisory guidance.

Remediation

Patch, then assume compromise.

Upgrade affected products to fixed versions: Firefox 152, Firefox ESR 140.12, Firefox ESR 115.37, Thunderbird 152, or Thunderbird 140.12, as applicable. Debian users should apply the corresponding firefox-esr package update referenced in DSA-6350-1. No more specific code-level remediation details are provided in the supplied content.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

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

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

7 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

7 SOURCESView more in app
What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
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Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

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

Social activity

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-12295
NVD
nvd.nist.gov/vuln/detail/CVE-2026-12295
MITRE CWE · CWE-693
cwe.mitre.org
bugzilla.mozilla.org
bugzilla.mozilla.org/show_bug.cgi?id=2040160
mozilla.org
mozilla.org/security/advisories/mfsa2026-57
mozilla.org
mozilla.org/security/advisories/mfsa2026-58
mozilla.org
mozilla.org/security/advisories/mfsa2026-59
mozilla.org
mozilla.org/security/advisories/mfsa2026-60
mozilla.org
mozilla.org/security/advisories/mfsa2026-61