If a template tag was used in a select tag,...

Vulnerability Description

If a template tag was used in a select tag, the parser could be confused and allow JavaScript parsing and execution when it should not be allowed. A site that relied on the browser behaving correctly could suffer a cross-site scripting vulnerability as a result. In general, this flaw cannot be exploited through email in the Thunderbird product because scripting is disabled when reading mail, but is potentially a risk in browser or browser-like contexts. This vulnerability affects Thunderbird < 68.5, Firefox < 73, and Firefox < ESR68.5.

References

• https://www.mozilla.org/security/advisories/mfsa2020-05/
• https://www.mozilla.org/security/advisories/mfsa2020-06/
• https://www.mozilla.org/security/advisories/mfsa2020-07/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1602944
• https://usn.ubuntu.com/4278-2/
• https://security.gentoo.org/glsa/202003-02
• https://security.gentoo.org/glsa/202003-10
• https://usn.ubuntu.com/4328-1/
• https://usn.ubuntu.com/4335-1/