How severe is CVE-2026-84127?

CVE-2026-84127 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2026-84127 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-84127?

CVE-2026-84127 affects Mozilla Firefox Mobile. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-84127?

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

When was CVE-2026-84127 published?

CVE-2026-84127 was published on 2026-09-01 and last updated on 2026-09-03.

CVE-2026-84127

CVE-2026-84127 is a medium-severity vulnerability in Mozilla Firefox Mobile with a CVSS 3.x base score of 4.3. 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-200.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Mozilla Firefox Mobile
Published: 2026-09-01
Last modified: 2026-09-03

Description

Information disclosure in the WebExtensions component in Firefox for Android. This vulnerability was fixed in Firefox 155.

Frequently asked questions

What is CVE-2026-84127?: Information disclosure in the WebExtensions component in Firefox for Android. This vulnerability was fixed in Firefox 155.
How severe is CVE-2026-84127?: CVE-2026-84127 has a CVSS 3.x base score of 4.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2026-84127 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-84127?: CVE-2026-84127 affects Mozilla Firefox Mobile. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-84127?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2026-84127 published?: CVE-2026-84127 was published on 2026-09-01 and last updated on 2026-09-03.

References

Affected products (1)

cpe:2.3:a:mozilla:firefox_mobile:*:*:*:*:*:android:*:*

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