How severe is CVE-2015-4516?

CVE-2015-4516 has a CVSS 2.0 base score of 9.3, rated critical severity.

Is CVE-2015-4516 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2015-4516?

CVE-2015-4516 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2015-4516?

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

When was CVE-2015-4516 published?

CVE-2015-4516 was published on 2015-09-24 and last updated on 2026-06-17.

CVE-2015-4516

CVE-2015-4516 is a critical-severity vulnerability in Mozilla Firefox with a CVSS 2.0 base score of 9.3. 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-254.

Key facts

Severity: Critical (CVSS 2.0 base score 9.3)
EPSS exploit prediction: 3% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-254
Affected product: Mozilla Firefox
Published: 2015-09-24
Last modified: 2026-06-17

Description

Mozilla Firefox before 41.0 allows remote attackers to bypass certain ECMAScript 5 (aka ES5) API protection mechanisms and modify immutable properties, and consequently execute arbitrary JavaScript code with chrome privileges, via a crafted web page that does not use ES5 APIs.

Frequently asked questions

What is CVE-2015-4516?: Mozilla Firefox before 41.0 allows remote attackers to bypass certain ECMAScript 5 (aka ES5) API protection mechanisms and modify immutable properties, and consequently execute arbitrary JavaScript code with chrome privileges, via a crafted web page that does not use ES5 APIs.
How severe is CVE-2015-4516?: CVE-2015-4516 has a CVSS 2.0 base score of 9.3, rated critical severity.
Is CVE-2015-4516 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2015-4516?: CVE-2015-4516 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2015-4516?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2015-4516 published?: CVE-2015-4516 was published on 2015-09-24 and last updated on 2026-06-17.

References

Affected products (1)

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

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