Thunderbird 45.6: Mozilla Update closes critical security holes

Emails can be a major security risk. Be alert and keep your mail program up-to-date.


Anyone who accesses the Thunderbird Thunderbird program from the Mozilla Foundation should quickly start the download of the update to version 45.6. With this, the organization fixes various vulnerabilities that allow attackers to inject and execute malicious program code on the computer of a potential victim. You can start the update by clicking "Help" / "About Thunderbird" in the title menu (under Windows, press the "Alt" key). The tool then displays the currently installed version, checks the Mozilla server for a newer version, and downloads it if necessary.


The Thunderbird versions for Windows, Mac OS and Linux are affected. The risk is very high, according to a short report by the Federal Office for Information Security (BSI). As the competent computer Emergency Response Team of the Federal Administration (CERT-Bund) writes, any attacker can send malicious code to Thunderbird versions older than the update 45.6, which allows for example the spying out of data or the bypassing of security precautions Br>

How Mozilla restricts itself in a security message is not an immediate threat of e-mail. Running scripts is disabled by default. Rather, potential risks may be expected in "browser- or browser-like contexts". You should therefore urgently avoid clicking into e-mails without consideration, which will be downloaded afterwards in your Internet browser or in Thunderbird itself. The biggest danger is spam mail.


As a further security precaution - this applies to every mail program - you should also disable the automatic retrieval of HTML content. Here you will find the settings of the respective tool. Thunderbird usually warns against reloading external content.