Updated thunderbird packages fix security vulnerabilities:
The iframe sandbox rules were not correctly applied to XSLT stylesheets,
allowing an iframe to bypass restrictions such as executing scripts or
navigating the top-level frame (CVE-2021-38503).
When interacting with an HTML input element's file picker dialog with
webkitdirectory set, a use-after-free could have resulted, leading to memory
corruption and a potentially exploitable crash (CVE-2021-38504).
Through a series of navigations, Thunderbird could have entered fullscreen
mode without notification or warning to the user. This could lead to spoofing
attacks on the browser UI including phishing (CVE-2021-38506).
The Opportunistic Encryption feature of HTTP2 (RFC 8164) allows a connection
to be transparently upgraded to TLS while retaining the visual properties of
an HTTP connection, including being same-origin with unencrypted connections
on port 80. However, if a second encrypted port on the same IP address (e.g.
port 8443) did not opt-in to opportunistic encryption; a network attacker
could forward a connection from the browser to port 443 to port 8443, causing
the browser to treat the content of port 8443 as same-origin with HTTP. This
was resolved by disabling the Opportunistic Encryption feature, which had low
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 (MOZ-2021-0008).
By displaying a form validity message in the correct location at the same time
as a permission prompt (such as for geolocation), the validity message could
have obscured the prompt, resulting in the user potentially being tricked into
granting the permission (CVE-2021-38508).
dialog with arbitrary (although unstyled) contents could be displayed over top
an uncontrolled webpage of the attacker's choosing (CVE-2021-38509).
Mozilla developers and community members Christian Holler, Valentin Gosu, and
Andrew McCreight reported memory safety bugs present in Thunderbird 91.2. Some
of these bugs showed evidence of memory corruption and we presume that with
enough effort some of these could have been exploited to run arbitrary code