How severe is CVE-2025-0240?

CVE-2025-0240 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.

Is CVE-2025-0240 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-0240?

CVE-2025-0240 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2025-0240?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2025-0240 have an EU (EUVD) identifier?

Yes. CVE-2025-0240 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-1572.

When was CVE-2025-0240 published?

CVE-2025-0240 was published on 2025-01-07 and last updated on 2026-06-17.

CVE-2025-0240

CVE-2025-0240 is a medium-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 4.0. 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-416.

Key facts

Severity: Medium (CVSS 3.x base score 4.0)
EPSS exploit prediction: 1% (47th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-1572
Weakness: CWE-416
Affected product: Mozilla Firefox
Published: 2025-01-07
Last modified: 2026-06-17

Description

Parsing a JavaScript module as JSON could, under some circumstances, cause cross-compartment access, which may result in a use-after-free. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.

Frequently asked questions

What is CVE-2025-0240?: Parsing a JavaScript module as JSON could, under some circumstances, cause cross-compartment access, which may result in a use-after-free. This vulnerability was fixed in Firefox 134, Firefox ESR 128.6, Thunderbird 134, and Thunderbird 128.6.
How severe is CVE-2025-0240?: CVE-2025-0240 has a CVSS 3.x base score of 4.0, rated medium severity. It is exploitable over local access with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability none.
Is CVE-2025-0240 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (47th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-0240?: CVE-2025-0240 primarily affects Mozilla Firefox. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2025-0240?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2025-0240 have an EU (EUVD) identifier?: Yes. CVE-2025-0240 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-1572.
When was CVE-2025-0240 published?: CVE-2025-0240 was published on 2025-01-07 and last updated on 2026-06-17.

References

Affected products (3)

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

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