How severe is CVE-2025-1943?

CVE-2025-1943 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.

Is CVE-2025-1943 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2025-1943?

CVE-2025-1943 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-2025-1943?

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

Does CVE-2025-1943 have an EU (EUVD) identifier?

Yes. CVE-2025-1943 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-6083.

When was CVE-2025-1943 published?

CVE-2025-1943 was published on 2025-03-04 and last updated on 2026-06-17.

CVE-2025-1943

CVE-2025-1943 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 8.2. 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-122.

Key facts

Severity: High (CVSS 3.x base score 8.2)
EPSS exploit prediction: 0% (32nd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2025-6083
Weakness: CWE-122
Affected product: Mozilla Firefox
Published: 2025-03-04
Last modified: 2026-06-17

Description

Memory safety bugs present in Firefox 135 and Thunderbird 135. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 136 and Thunderbird 136.

Frequently asked questions

What is CVE-2025-1943?: Memory safety bugs present in Firefox 135 and Thunderbird 135. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 136 and Thunderbird 136.
How severe is CVE-2025-1943?: CVE-2025-1943 has a CVSS 3.x base score of 8.2, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity low, and availability high.
Is CVE-2025-1943 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (32nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2025-1943?: CVE-2025-1943 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-2025-1943?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2025-1943 have an EU (EUVD) identifier?: Yes. CVE-2025-1943 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2025-6083.
When was CVE-2025-1943 published?: CVE-2025-1943 was published on 2025-03-04 and last updated on 2026-06-17.

References

Affected products (2)

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

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