CVE-2016-9079: Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerability

Is it exploited?

Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 22 Jun 2023, 1,837 days after the CVE record was published.

How likely is exploitation in the next 30 days?

87.4%

EPSS score, percentile 99.8 of all scored records

How severe?

7.5 High

CVSS v3.1 base score, from CISA's enrichment of the record

What should I do?

Required action (CISA), due 13 Jul 2023: Apply updates per vendor instructions.

Advisories and patches (5)

Which versions are affected?

Affected: before 50.0.2; before 45.5.1; before 45.5.1

Versions by product

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

What to do

CISA due date for this action: 13 July 2023.

Advisories and patches

• DSA-3730 (Vendor advisory)
• RHSA-2016:2843 (Vendor advisory)
• GLSA-201701-35 (Vendor advisory)
• RHSA-2016:2850 (Vendor advisory)
• GLSA-201701-15 (Vendor advisory)

Linked from CISA's catalog entry

• https://www.mozilla.org/en-US/security/advisories/mfsa2016-92/#CVE-2016-9079
• https://nvd.nist.gov/vuln/detail/CVE-2016-9079

Affected products and versions

As listed in the CVE record.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

About this vulnerability

Mozilla Firefox, Firefox ESR, and Thunderbird contain a use-after-free vulnerability in SVG Animation, targeting Firefox and Tor browser users on Windows.

Summary: CISA's KEV catalog, as of 28 Oct 2026.

• CISA added CVE-2016-9079 to its Known Exploited Vulnerabilities (KEV) catalog on 22 Jun 2023.
• CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
• The due date CISA sets for the required action is 13 Jul 2023.
• The CVE record was published on 11 Jun 2018, 1,837 days before it was added to KEV.
• The CVE record carries a CVSS v3.1 base score of 7.5 (High), taken from CISA's enrichment of the record.
• FIRST's EPSS model puts the probability of exploitation in the next 30 days at 87.4% (percentile 99.8), as of 28 Oct 2026.
• CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.

Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.

Description

A use-after-free vulnerability in SVG Animation has been discovered. An exploit built on this vulnerability has been discovered in the wild targeting Firefox and Tor Browser users on Windows. This vulnerability affects Firefox < 50.0.2, Firefox ESR < 45.5.1, and Thunderbird < 45.5.1.

Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.

Weakness

• CWE-416: Use After Free

CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.

Timeline

References

• 42327 (Exploit)
• 41151 (Exploit)
• 1037370 (Vulnerability database)
• 94591 (Vulnerability database)
• mozilla.org
• bugzilla.mozilla.org

More exploited Mozilla vulnerabilities

• CVE-2010-3765: Mozilla Multiple Products Remote Code Execution Vulnerability (added 6 Oct 2025)
• CVE-2024-9680: Mozilla Firefox Use-After-Free Vulnerability (added 15 Oct 2024)
• CVE-2015-4495: Mozilla Firefox Security Feature Bypass Vulnerability (added 25 May 2022)
• CVE-2019-11707: Mozilla Firefox and Thunderbird Type Confusion Vulnerability (added 23 May 2022)
• CVE-2019-11708: Mozilla Firefox and Thunderbird Sandbox Escape Vulnerability (added 23 May 2022)
• CVE-2013-1690: Mozilla Firefox and Thunderbird Denial-of-Service Vulnerability (added 28 Mar 2022)