How severe is CVE-2016-1949?

CVE-2016-1949 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-2016-1949 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2016-1949?

CVE-2016-1949 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2016-1949?

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-2016-1949 published?

CVE-2016-1949 was published on 2016-02-13 and last updated on 2026-06-17.

CVE-2016-1949

CVE-2016-1949 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-264.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.8
EPSS exploit prediction: 2% (71st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-264
Affected product: Mozilla Firefox
Published: 2016-02-13
Last modified: 2026-06-17

Description

Mozilla Firefox before 44.0.2 does not properly restrict the interaction between Service Workers and plugins, which allows remote attackers to bypass the Same Origin Policy via a crafted web site that triggers spoofed responses to requests that use NPAPI, as demonstrated by a request for a crossdomain.xml file.

Frequently asked questions

What is CVE-2016-1949?: Mozilla Firefox before 44.0.2 does not properly restrict the interaction between Service Workers and plugins, which allows remote attackers to bypass the Same Origin Policy via a crafted web site that triggers spoofed responses to requests that use NPAPI, as demonstrated by a request for a crossdomain.xml file.
How severe is CVE-2016-1949?: CVE-2016-1949 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-2016-1949 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (71st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2016-1949?: CVE-2016-1949 affects Mozilla Firefox. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2016-1949?: 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-2016-1949 published?: CVE-2016-1949 was published on 2016-02-13 and last updated on 2026-06-17.

References

Affected products (1)

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

More vulnerabilities in Mozilla Firefox

CVE-2026-4725 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Graphics: Canvas2D component. This vulnerability was fixed in Firefox 149…
CVE-2026-4692 — Critical (CVSS 10.0): Sandbox escape in the Responsive Design Mode component. This vulnerability was fixed in Firefox 149, Firefox ESR…
CVE-2026-4689 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions, integer overflow in the XPCOM component. This vulnerability was…
CVE-2026-4688 — Critical (CVSS 10.0): Sandbox escape due to use-after-free in the Disability Access APIs component. This vulnerability was fixed in Firefox…
CVE-2026-2778 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the DOM: Core & HTML component. This vulnerability was fixed in…
CVE-2026-2776 — Critical (CVSS 10.0): Sandbox escape due to incorrect boundary conditions in the Telemetry component in External Software. This vulnerability…

All CVEs affecting Mozilla Firefox →

Other CWE-264 (Permissions, Privileges, and Access Controls) vulnerabilities

CVE-2016-8363 — Critical (CVSS 10.0): An issue was discovered in Moxa OnCell OnCellG3470A-LTE, AWK-1131A/3131A/4131A Series, AWK-3191 Series, AWK-5232/6232…
CVE-2016-7457 — Critical (CVSS 10.0): VMware vRealize Operations (aka vROps) 6.x before 6.4.0 allows remote authenticated users to gain privileges, or halt…
CVE-2015-7425 — Critical (CVSS 10.0): The Data Protection component in the VMware vSphere GUI in IBM Tivoli Storage Manager for Virtual Environments: Data…
CVE-2015-8267 — Critical (CVSS 10.0): The PasswordReset.Controllers.ResetController.ChangePasswordIndex method in PasswordReset.dll in Dovestones AD Self…
CVE-2015-7919 — Critical (CVSS 10.0): SearchBlox 8.3 before 8.3.1 allows remote attackers to write to the config file, and consequently cause a denial of…
CVE-2015-7071 — Critical (CVSS 10.0): The File Bookmark component in Apple OS X before 10.11.2 allows attackers to bypass a sandbox protection mechanism for…

Browse all CWE-264 (Permissions, Privileges, and Access Controls) vulnerabilities →