How severe is CVE-2026-92066?

CVE-2026-92066 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-92066 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-92066?

CVE-2026-92066 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-92066?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-92066 published?

CVE-2026-92066 was published on 2026-09-15 and last updated on 2026-10-05.

CVE-2026-92066

CVE-2026-92066 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-693.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 1% (44th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-693
Affected product: Mozilla Firefox
Published: 2026-09-15
Last modified: 2026-10-05

Description

Sandbox escape in the Profile Backup component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.

Frequently asked questions

What is CVE-2026-92066?: Sandbox escape in the Profile Backup component. This vulnerability was fixed in Firefox 156 and Thunderbird 156.
How severe is CVE-2026-92066?: CVE-2026-92066 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-92066 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (44th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-92066?: CVE-2026-92066 primarily affects Mozilla Firefox. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-92066?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-92066 published?: CVE-2026-92066 was published on 2026-09-15 and last updated on 2026-10-05.

References

Affected products (2)

cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

More vulnerabilities in Mozilla Firefox

CVE-2026-75874 — Critical (CVSS 10.0): Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154,…
CVE-2026-16367 — Critical (CVSS 10.0): Sandbox escape due to invalid pointer in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4692 — Critical (CVSS 10.0): Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR…
CVE-2026-4689 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…

All CVEs affecting Mozilla Firefox →

Other CWE-693 (Protection Mechanism Failure) vulnerabilities

CVE-2026-93606 — Critical (CVSS 10.0): vm2 (npm) versions 3.12.0 and earlier contain a sandbox escape in `VM` and `NodeVM`. When an embedder exposes a host…
CVE-2026-93605 — Critical (CVSS 10.0): vm2 NodeVM versions before 3.12.1 contain a sandbox escape vulnerability where the DANGEROUS_BUILTINS denylist omits…
CVE-2026-92956 — Critical (CVSS 10.0): vm2 versions 3.10.1 through 3.11.6 contain a sandbox escape reachable from a default `new VM()` sandbox when running on…
CVE-2026-75874 — Critical (CVSS 10.0): Sandbox escape in the Remote Settings Client component. This vulnerability was fixed in Firefox 154, Thunderbird 154,…
CVE-2026-47140 — Critical (CVSS 10.0): vm2 is an open source vm/sandbox for Node.js. Prior to version 3.11.4, NodeVM blocks several dangerous Node.js builtins…
CVE-2026-34208 — Critical (CVSS 10.0): SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, SandboxJS blocks direct assignment to global objects…

Browse all CWE-693 (Protection Mechanism Failure) vulnerabilities →