Incorrect handling of __proto__ mutations may lead to type confusion in IonMonkey JIT code and can be leveraged for arbitrary memory read…

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.

Scores

EPSS (exploitation in 30 days)

6.7% · top 6.0% of all CVEs (5 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.8.

Weakness

• Ionmonkey type confusion with __proto__ mutations
• CWE-843 (opens in a new tab)All about CWE-843 and its CVEs

Affected products

• Mozilla · Firefox

  • affected unspecified – < 66.0.1

• Mozilla · Firefox ESR

  • affected unspecified – < 60.6.1

• Mozilla · Thunderbird

  • affected unspecified – < 60.6.1

References (6)

• https://www.mozilla.org/security/advisories/mfsa2019-09/ (opens in a new tab)x_refsource_MISCx_transferred
• https://www.mozilla.org/security/advisories/mfsa2019-10/ (opens in a new tab)x_refsource_MISCx_transferred
• https://www.mozilla.org/security/advisories/mfsa2019-12/ (opens in a new tab)x_refsource_MISCx_transferred
• https://bugzilla.mozilla.org/show_bug.cgi?id=1538006 (opens in a new tab)x_refsource_MISCx_transferred
• RHSA-2019:0966 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred
• RHSA-2019:1144 (opens in a new tab)vendor-advisoryx_refsource_REDHATx_transferred

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2019-9813](https://trackcve.app/badge/CVE-2019-9813.svg)](https://trackcve.app/cve/CVE-2019-9813)

Record last updated 4 Aug 2024, 22:01 UTC.