CVE-2016-1974

CVE-2016-1974 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

Description

The nsScannerString::AppendUnicodeTo function in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 does not verify that memory allocation succeeds, which allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read) via crafted Unicode data in an HTML, XML, or SVG document.

Frequently asked questions

What is CVE-2016-1974?
The nsScannerString::AppendUnicodeTo function in Mozilla Firefox before 45.0 and Firefox ESR 38.x before 38.7 does not verify that memory allocation succeeds, which allows remote attackers to execute arbitrary code or cause a denial of service (out-of-bounds read) via crafted Unicode data in an HTML, XML, or SVG document.
How severe is CVE-2016-1974?
CVE-2016-1974 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-2016-1974 being actively exploited?
It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-1974?
CVE-2016-1974 primarily affects Mozilla Firefox. In total, 22 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2016-1974?
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.
When was CVE-2016-1974 published?
CVE-2016-1974 was published on 2016-03-13 and last updated on 2026-06-17.

References

Affected products (22)

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