A use-after-free could have occured when an HTTP2 session object was released on a different thread, leading to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox < 93, Thunderbird < 91.3, and Firefox ESR < 91.3.
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 Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Firefox | Mozilla | * | 93.0 (excluding) |
| Firefox_esr | Mozilla | * | 91.3.0 (excluding) |
| Thunderbird | Mozilla | * | 91.3.0 (excluding) |
| Red Hat Enterprise Linux 7 | RedHat | firefox-0:91.3.0-1.el7_9 | * |
| Red Hat Enterprise Linux 7 | RedHat | thunderbird-0:91.3.0-2.el7_9 | * |
| Red Hat Enterprise Linux 8 | RedHat | firefox-0:91.3.0-1.el8_4 | * |
| Red Hat Enterprise Linux 8 | RedHat | thunderbird-0:91.3.0-2.el8_4 | * |
| Red Hat Enterprise Linux 8.1 Extended Update Support | RedHat | thunderbird-0:91.3.0-2.el8_1 | * |
| Red Hat Enterprise Linux 8.1 Extended Update Support | RedHat | firefox-0:91.3.0-1.el8_1 | * |
| Red Hat Enterprise Linux 8.2 Extended Update Support | RedHat | thunderbird-0:91.3.0-2.el8_2 | * |
| Red Hat Enterprise Linux 8.2 Extended Update Support | RedHat | firefox-0:91.3.0-1.el8_2 | * |
| Firefox | Ubuntu | trusty | * |
| Firefox | Ubuntu | xenial | * |
| Thunderbird | Ubuntu | bionic | * |
| Thunderbird | Ubuntu | focal | * |
| Thunderbird | Ubuntu | hirsute | * |
| Thunderbird | Ubuntu | trusty | * |
| Thunderbird | Ubuntu | xenial | * |