During browser shutdown, reference decrementing could have occured on a previously freed object, resulting in a use-after-free, memory corruption, and a potentially exploitable crash. This vulnerability affects Firefox < 83, Firefox ESR < 78.5, and Thunderbird < 78.5.
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 Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.
| Link | Tags |
|---|---|
| https://bugzilla.mozilla.org/show_bug.cgi?id=1669466 | issue tracking permissions required vendor advisory |
| https://www.mozilla.org/security/advisories/mfsa2020-50/ | vendor advisory |
| https://www.mozilla.org/security/advisories/mfsa2020-52/ | vendor advisory |
| https://www.mozilla.org/security/advisories/mfsa2020-51/ | vendor advisory |