How severe is CVE-2016-5251?

CVE-2016-5251 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-2016-5251 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-5251?

CVE-2016-5251 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-5251?

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

When was CVE-2016-5251 published?

CVE-2016-5251 was published on 2016-08-05 and last updated on 2026-06-17.

CVE-2016-5251

CVE-2016-5251 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. The underlying weakness is classified as CWE-20.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
CVSS v2: 4.3
EPSS exploit prediction: 1% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Mozilla Firefox
Published: 2016-08-05
Last modified: 2026-06-17

Description

Mozilla Firefox before 48.0 allows remote attackers to spoof the location bar via crafted characters in the media type of a data: URL.

Frequently asked questions

What is CVE-2016-5251?: Mozilla Firefox before 48.0 allows remote attackers to spoof the location bar via crafted characters in the media type of a data: URL.
How severe is CVE-2016-5251?: CVE-2016-5251 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-2016-5251 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-5251?: CVE-2016-5251 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-5251?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2016-5251 published?: CVE-2016-5251 was published on 2016-08-05 and last updated on 2026-06-17.

References

Affected products (1)

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

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