How severe is CVE-2025-4083?

CVE-2025-4083 has a CVSS 3.x base score of 9.1, 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 none.

Is CVE-2025-4083 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-4083?

CVE-2025-4083 primarily affects Mozilla Firefox. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-4083?

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.

Does CVE-2025-4083 have an EU (EUVD) identifier?

Yes. CVE-2025-4083 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12730.

When was CVE-2025-4083 published?

CVE-2025-4083 was published on 2025-04-29 and last updated on 2026-06-17.

CVE-2025-4083

CVE-2025-4083 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 9.1. 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-653.

Key facts

Severity: Critical (CVSS 3.x base score 9.1)
EPSS exploit prediction: 0% (30th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-12730
Weakness: CWE-653
Affected product: Mozilla Firefox
Published: 2025-04-29
Last modified: 2026-06-17

Description

A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.

Frequently asked questions

What is CVE-2025-4083?: A process isolation vulnerability in Thunderbird stemmed from improper handling of javascript: URIs, which could allow content to execute in the top-level document's process instead of the intended frame, potentially enabling a sandbox escape. This vulnerability was fixed in Firefox 138, Firefox ESR 128.10, Firefox ESR 115.23, Thunderbird 138, and Thunderbird 128.10.
How severe is CVE-2025-4083?: CVE-2025-4083 has a CVSS 3.x base score of 9.1, 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 none.
Is CVE-2025-4083 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (30th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-4083?: CVE-2025-4083 primarily affects Mozilla Firefox. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-4083?: 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.
Does CVE-2025-4083 have an EU (EUVD) identifier?: Yes. CVE-2025-4083 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-12730.
When was CVE-2025-4083 published?: CVE-2025-4083 was published on 2025-04-29 and last updated on 2026-06-17.

References

Affected products (4)

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

More vulnerabilities in Mozilla 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…
CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…

All CVEs affecting Mozilla Firefox →

Other CWE-653 vulnerabilities

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-2025-1974 — Critical (CVSS 9.8): A security issue was discovered in Kubernetes where under certain conditions, an unauthenticated attacker with access…
CVE-2024-33768 — Critical (CVSS 9.8): lunasvg v2.3.9 was discovered to contain a segmentation violation via the component composition_solid_source_over.
CVE-2026-0542 — Critical (CVSS 9.2): ServiceNow has addressed a remote code execution vulnerability that was identified in the ServiceNow AI platform. This…
CVE-2025-5476 — High (CVSS 8.8): Sony XAV-AX8500 Bluetooth Improper Isolation Authentication Bypass Vulnerability. This vulnerability allows…
CVE-2024-23683 — High (CVSS 8.2): Artemis Java Test Sandbox versions less than 1.7.6 are vulnerable to a sandbox escape when an attacker crafts a special…

Browse all CWE-653 vulnerabilities →