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AUSCERT External Security Bulletin Redistribution
MFSA 2020-26 Security Vulnerabilities fixed in Thunderbird 68.10.0
3 July 2020
AusCERT Security Bulletin Summary
Operating System: Windows
UNIX variants (UNIX, Linux, OSX)
Impact/Access: Denial of Service -- Unknown/Unspecified
Access Confidential Data -- Unknown/Unspecified
CVE Names: CVE-2020-12421 CVE-2020-12420 CVE-2020-12419
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Mozilla Foundation Security Advisory 2020-26
Security Vulnerabilities fixed in Thunderbird 68.10.0
June 30, 2020
In general, these flaws cannot be exploited through email in the Thunderbird
product because scripting is disabled when reading mail, but are potentially
risks in browser or browser-like contexts.
# CVE-2020-12417: Memory corruption due to missing sign-extension for ValueTags
through the type barrier, resulting in memory corruption and a potentially
Note: this issue only affects Firefox on ARM64 platforms.
o Bug 1640737
# CVE-2020-12418: Information disclosure due to manipulated URL object
Marcin 'Icewall' Noga of Cisco Talos
Manipulating individual parts of a URL object could have caused an
o Bug 1641303
# CVE-2020-12419: Use-after-free in nsGlobalWindowInner
When processing callbacks that occurred during window flushing in the parent
process, the associated window may die; causing a use-after-free condition.
This could have led to memory corruption and a potentially exploitable crash.
o Bug 1643874
# CVE-2020-12420: Use-After-Free when trying to connect to a STUN server
When trying to connect to a STUN server, a race condition could have caused a
use-after-free of a pointer, leading to memory corruption and a potentially
o Bug 1643437
# MFSA-2020-0001: Automatic account setup leaks Microsoft Exchange login
If an attacker intercepts Thunderbird's initial attempt to perform automatic
account setup using the Microsoft Exchange autodiscovery mechanism, and the
attacker sends a crafted response, then Thunderbird sends username and password
over https to a server controlled by the attacker.
Note: This issue is pending a CVE assignment and will be updated when one is
o Bug 1606610
# CVE-2020-12421: Add-On updates did not respect the same certificate trust
rules as software updates
Chuck Harmston, Robert Hardy
When performing add-on updates, certificate chains terminating in
non-built-in-roots were rejected (even if they were legitimately added by an
administrator.) This could have caused add-ons to become out-of-date silently
without notification to the user.
o Bug 1308251
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