Firefox 77, Tor Browser 9.5 Released With Patches, Security Improvements

03 June 2020

Firefox 77, Tor Browser 9.5 Released With Patches, Security Improvements

Firefox 77 and Tor Browser 9.5 were released this week with patches for a variety of vulnerabilities, including several rated high severity.

Mozilla’s browser arrived with a total of 8 security fixes, including 5 that address high severity issues.

The most important of these is a patch for CVE-2020-12399, a timing attack on DSA signatures in the NSS library: due to timing differences when performing DSA signatures, an adversary could devise an attack and leak private keys.

Another high risk flaw addressed in this release was a use-after-free in SharedWorkerService (CVE-2020-12405), triggered by a race condition that could occur when browsing a malicious page. Additionally, Mozilla patched a JavaScript type confusion with NativeTypes (CVE-2020-12406).

A medium risk issue was patched in Firefox 77 this week, where, under certain conditions, arbitrary GPU memory would be leaked to the visible screen. Two low severity bugs were fixed, both URL spoofing issues.

Mozilla also addressed a series of high severity memory safety bugs in both Firefox 77 and Firefox ESR 68.9. The newly released Tor Browser 9.5 is based on the latter.

In addition to the security fixes in Firefox ESR 68.9 (addressing the aforementioned high risk flaws), the latest Tor release brings several other security improvements, such as the option to select the .onion version of a visited website, where one exists, or onion services administrators’ ability to set a pair of keys for access control and authentication to their website.

Starting with Tor Browser 9.5, if Onion Location is enabled, users will be informed when a website also has an .onion address and will be provided with the option to choose that instead. Moreover, they can set the browser to always use the .onion address when available.

For websites where authentication keys are used as an additional layer of security, Tor Browser users can have those keys saved in their browser, and can head to about:preferences#privacy to manage them, in the Onion Services Authentication section.

The latest Tor Browser release also comes with updated security indicators, so that users can more easily understand when they are accessing non-secure websites, as well as with updated error messages for onion services, so that users better understand why they were unable to connect.

In partnership with Freedom of the Press Foundation (FPF) and the Electronic Frontier Foundation's HTTPS Everywhere, Tor is working on the development of proof-of-concept human-memorable names for SecureDrop onion services addresses.

Additionally, the browser includes a series of other bug fixes and improvements, for all of the supported operating systems: Windows, macOS, Linux, and Android.