How severe is CVE-2026-3847?

CVE-2026-3847 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-3847 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-3847?

CVE-2026-3847 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-3847?

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-2026-3847 have an EU (EUVD) identifier?

Yes. CVE-2026-3847 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10506.

When was CVE-2026-3847 published?

CVE-2026-3847 was published on 2026-03-10 and last updated on 2026-06-17.

CVE-2026-3847

CVE-2026-3847 is a high-severity vulnerability in Mozilla Firefox with a CVSS 3.x base score of 8.8. 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-119.

Key facts

Severity: High (CVSS 3.x base score 8.8)
EPSS exploit prediction: 0% (23rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10506
Weakness: CWE-119
Affected product: Mozilla Firefox
Published: 2026-03-10
Last modified: 2026-06-17

Description

Memory safety bugs present in Firefox 148.0.2. 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 148.0.2.

Frequently asked questions

What is CVE-2026-3847?: Memory safety bugs present in Firefox 148.0.2. 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 148.0.2.
How severe is CVE-2026-3847?: CVE-2026-3847 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-3847 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (23rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-3847?: CVE-2026-3847 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-3847?: 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-2026-3847 have an EU (EUVD) identifier?: Yes. CVE-2026-3847 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10506.
When was CVE-2026-3847 published?: CVE-2026-3847 was published on 2026-03-10 and last updated on 2026-06-17.

References

Affected products (1)

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

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