IRONSMITHINTEL
HIGHCVSS7.5
|
Actively Exploited
|CISA KEV|CVE-2016-9079|Auth: none — unauthenticated|Reboot: required|Manual only

Mozilla Firefox, Firefox ESR, and Thunderbird Use-After-Free Vulnerability

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

Published Jun 11, 2018 · Updated May 16, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve full data confidentiality loss. Federal agencies are required to remediate by 2023-07-13 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Use After Free (CWE-416) vulnerability in Mozilla Firefox, Firefox ESR, and Thunderbird. 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. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

●IT Security
●Running debian linux: 9.0; enterprise linux: 5.0, 6.0, 7.0; enterprise linux desktop: 5.0, 6.0, 7.0; enterprise linux server: 5.0, 6.0, 7.0; enterprise linux server aus: 7.3, 7.4; enterprise linux server eus: 7.3, 7.4, 7.5; enterprise linux workstation: 5.0, 6.0, 7.0; thunderbird: v < 45.5.1; firefox: v < 50.0.2, v < 45.5.1; tor: -
Real-world incidentsWhat we've seen

Active exploitation documented in the wild. Threat-research write-up: https://bugzilla.mozilla.org/show_bug.cgi?id=1321066

How to patch

Manual remediation steps

Apply the Vendor Patch

This vulnerability is in the CISA Known Exploited Vulnerabilities catalog — apply the vendor's security update as soon as possible.

CISA required action: Apply updates per vendor instructions.

References

    1
    Vendor advisory: https://www.mozilla.org/en-US/security/advisories/mfsa2016-92/#CVE-2016-9079
    1
    NVD entry: https://nvd.nist.gov/vuln/detail/CVE-2016-9079
    1
    CISA KEV: https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2016-9079
PowerShell automationComing soon

No tested PowerShell script for this entry yet. We’re prioritising automation based on user demand.

References

↗ CVE-2016-9079↗ NVD↗ Vendor Advisory