How severe is CVE-2023-6871?

CVE-2023-6871 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 none, integrity low, and availability none.

Is CVE-2023-6871 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2023-6871?

CVE-2023-6871 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2023-6871?

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

When was CVE-2023-6871 published?

CVE-2023-6871 was published on 2023-12-19 and last updated on 2026-06-17.

CVE-2023-6871

CVE-2023-6871 is a medium-severity vulnerability in Mozilla Firefox 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.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (39th percentile)
Actively exploited: Not listed in CISA KEV
Affected product: Mozilla Firefox
Published: 2023-12-19
Last modified: 2026-06-17

Description

Under certain conditions, Firefox did not display a warning when a user attempted to navigate to a new protocol handler. This vulnerability affects Firefox < 121.

Frequently asked questions

What is CVE-2023-6871?: Under certain conditions, Firefox did not display a warning when a user attempted to navigate to a new protocol handler. This vulnerability affects Firefox < 121.
How severe is CVE-2023-6871?: CVE-2023-6871 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 none, integrity low, and availability none.
Is CVE-2023-6871 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (39th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2023-6871?: CVE-2023-6871 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2023-6871?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2023-6871 published?: CVE-2023-6871 was published on 2023-12-19 and last updated on 2026-06-17.

References

Affected products (1)

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

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