CVE-2025-14330

JIT miscompilation in the JavaScript Engine: JIT component

Published Dec 9, 2025 CVSS 3.1 · 9.8 Critical EPSS < 1% KEV · Not listed

Description

JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 146, Firefox ESR 140.6, Thunderbird 146, and Thunderbird 140.6.

Analysis

Technical impact

JIT miscompilation in the JavaScript Engine: JIT component allows the Just‑In‑Time compiler to produce incorrect machine code, which can corrupt application memory. The corruption can potentially enable a malicious actor to execute arbitrary code within the browser or its extensions. The weakness involves improper memory handling (CWE‑119), erroneous computation (CWE‑686), and data type confusion (CWE‑843).

Affected Systems

Mozilla Firefox and Thunderbird are affected. The flaw was fixed in Firefox 146 and Firefox ESR 140.6, and in Thunderbird 146 and Thunderbird ESR 140.6; earlier releases before these versions contain the vulnerability.

Risk and Exploitability

The CVSS base score of 9.8 indicates critical severity. The EPSS score of < 1 % indicates that widespread exploitation has not yet been observed. Based on the description, the likely attack vector is a malicious JavaScript payload served from an untrusted web page or resource, allowing the miscompilation to be triggered remotely. The vulnerability is not listed in CISA’s KEV catalog, so no public exploits are known, but a zero‑day exploitation remains a possibility until the affected builds are updated.

Affected Products

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Mozilla

Firefox

affected

Version	Status	Constraints
`140.6`	unaffected	≤ 140.*
`146`	unaffected	≤ *

Mozilla

Thunderbird

affected

Version	Status	Constraints
`140.6`	unaffected	≤ 140.*
`146`	unaffected	≤ *

Configuration 1 [-]

OR	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:::::-:::*

No data.

Vendor	Product	Versions
Mozilla	Firefox	—
Mozilla	Firefox Esr	—

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

Upgrade Firefox to 146 or newer (or ESR 140.6 or newer) and Thunderbird to 146 or newer (or ESR 140.6 or newer).
If an upgrade is not possible at the moment, disable the JIT compiler through enterprise configuration or command‑line flags to mitigate the miscompilation risk until a point release is applied.
Apply a strict Content Security Policy that blocks JavaScript from untrusted origins to reduce the chance that a malicious payload can execute in the compromised JIT context.

Generated by OpenCVE AI on April 20, 2026 at 21:32 UTC.

Tracking

Advisories

Source	ID	Title
Debian DLA	DLA-4401-1	firefox-esr security update
Debian DLA	DLA-4405-1	thunderbird security update
Debian DSA	DSA-6078-1	firefox-esr security update
Debian DSA	DSA-6081-1	thunderbird security update
Ubuntu USN	USN-7991-1	Thunderbird vulnerabilities

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Unchanged

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploit prediction score: < 1% (0.542% probability within 30 days)

Exploitation none

Automatable yes

Technical Impact total

References

Link	Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=1997503
https://nvd.nist.gov/vuln/detail/CVE-2025-14330
https://www.cve.org/CVERecord?id=CVE-2025-14330
https://www.mozilla.org/security/advisories/mfsa2025-92/
https://www.mozilla.org/security/advisories/mfsa2025-94/
https://www.mozilla.org/security/advisories/mfsa2025-94/#CVE-2025-14330
https://www.mozilla.org/security/advisories/mfsa2025-95/
https://www.mozilla.org/security/advisories/mfsa2025-96/

History

Apr 13, 2026 3:00 PM Description updated View changes

Type	Values Removed	Values Added
Description	JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 146, Firefox ESR < 140.6, Thunderbird < 146, and Thunderbird < 140.6.	JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 146, Firefox ESR 140.6, Thunderbird 146, and Thunderbird 140.6.

Dec 11, 2025 9:15 PM Weaknesses updated. Scoring metrics updated View changes

Type	Values Removed	Values Added
Weaknesses		CWE-119 CWE-686 CWE-843
Metrics		ssvc `{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}`

Dec 10, 2025 8:30 PM First appearance in the feed. Weaknesses updated. Affected versions updated. Affected vendors updated. Scoring metrics updated View changes

Type	Values Removed	Values Added
First Time appeared		Mozilla thunderbird
Weaknesses		NVD-CWE-noinfo
CPEs		cpe:2.3:a:mozilla:firefox:::::-:::* cpe:2.3:a:mozilla:firefox:::::esr:::* cpe:2.3:a:mozilla:thunderbird:::::-:::* cpe:2.3:a:mozilla:thunderbird:::::esr:::*
Vendors & Products		Mozilla thunderbird
Metrics	cvssV3_1 `{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}`	cvssV3_1 `{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}`

Dec 10, 2025 6:00 PM First appearance in the feed. Affected vendors updated View changes

Type	Values Removed	Values Added
First Time appeared		Mozilla Mozilla firefox Mozilla firefox Esr
Vendors & Products		Mozilla Mozilla firefox Mozilla firefox Esr

Dec 10, 2025 2:45 PM Description updated. Added references View changes

Type	Values Removed	Values Added
Description	JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 146 and Firefox ESR < 140.6.	JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 146, Firefox ESR < 140.6, Thunderbird < 146, and Thunderbird < 140.6.
References		https://www.mozilla.org/security/advisories/mfsa2025-95/ https://www.mozilla.org/security/advisories/mfsa2025-96/

Dec 10, 2025 12:15 AM Added references. Scoring metrics updated View changes

Type	Values Removed	Values Added
References		https://nvd.nist.gov/vuln/detail/CVE-2025-14330 https://www.cve.org/CVERecord?id=CVE-2025-14330 https://www.mozilla.org/security/advisories/mfsa2025-94/#CVE-2025-14330
Metrics	threat_severity `None`	cvssV3_1 `{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}` threat_severity `Moderate`

Dec 9, 2025 1:45 PM Description updated. Title updated. Added references View changes

Type	Values Removed	Values Added
Description		JIT miscompilation in the JavaScript Engine: JIT component. This vulnerability affects Firefox < 146 and Firefox ESR < 140.6.
Title		JIT miscompilation in the JavaScript Engine: JIT component
References		https://bugzilla.mozilla.org/show_bug.cgi?id=1997503 https://www.mozilla.org/security/advisories/mfsa2025-92/ https://www.mozilla.org/security/advisories/mfsa2025-94/