CVE-2019-11691

Description

A use-after-free vulnerability can occur when working with XMLHttpRequest (XHR) in an event loop, causing the XHR main thread to be called after it has been freed. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

CVSS Metrics

• v3.0•CRITICAL•Score: 9.8CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• v2.0•HIGH•Score: 7.5AV:N/AC:L/Au:N/C:P/I:P/A:P

EPSS Trends

Current EPSS score: 0.73%• Percentile: 73%

Techniques & Countermeasures

• CWE-416•Use After Free

  The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

Affected Systems

• mozilla•firefox

  < 67.0 | ≥ unspecified, < 67

• mozilla•firefox_esr

  < 60.7 | ≥ unspecified, < 60.7

• mozilla•thunderbird

  < 60.7 | ≥ unspecified, < 60.7

References (4)

• https://www.mozilla.org/security/advisories/mfsa2019-13/
• https://www.mozilla.org/security/advisories/mfsa2019-15/
• https://www.mozilla.org/security/advisories/mfsa2019-14/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1542465