Mozilla · Firefox Esr · CVE-2023-6209
**Name of the Vulnerable Software and Affected Versions**
Firefox versions prior to 120
Firefox ESR versions prior to 115.5.0
Thunderbird versions prior to 115.5
**Description**
The issue is related to the incorrect parsing of relative URLs starting with three slashes, allowing a path-traversal `/../` part in the path to override the specified host. This could contribute to security problems in web sites. The vulnerability may allow a remote attacker to gain unauthorized access to protected information.
**Recommendations**
For Firefox versions prior to 120, update to version 120 or later.
For Firefox ESR versions prior to 115.5.0, update to version 115.5.0 or later.
For Thunderbird versions prior to 115.5, update to version 115.5 or later.