What’s Vulnerable › Vulnerabilities

CVE-2019-9813

• Severity: high (CVSS 8.8 v3.0)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 6.7% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2019-04-26 · updated 2026-06-17
• Weakness: CWE-843

Description

Incorrect handling of __proto__ mutations may lead to type confusion in IonMonkey JIT code and can be leveraged for arbitrary memory read and write. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.

Affected products

• Mozilla Firefox: before 60.6.1; before 66.0.1 — fixed in 60.6.1, 66.0.1
• Mozilla Thunderbird: before 60.6.1 — fixed in 60.6.1

How to fix

Upgrade to a fixed version: Mozilla Firefox 60.6.1, 66.0.1; Mozilla Thunderbird 60.6.1. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2019:0966
• https://access.redhat.com/errata/RHSA-2019:1144
• https://bugzilla.mozilla.org/show_bug.cgi?id=1538006
• https://www.mozilla.org/security/advisories/mfsa2019-09/
• https://www.mozilla.org/security/advisories/mfsa2019-10/
• https://www.mozilla.org/security/advisories/mfsa2019-12/
• https://access.redhat.com/errata/RHSA-2019:0966
• https://access.redhat.com/errata/RHSA-2019:1144
• https://bugzilla.mozilla.org/show_bug.cgi?id=1538006
• https://www.mozilla.org/security/advisories/mfsa2019-09/
• https://www.mozilla.org/security/advisories/mfsa2019-10/
• https://www.mozilla.org/security/advisories/mfsa2019-12/

Get alerted when CVE-2019-9813 or the next vulnerability affects your stack