CVE-2019-3902

Starting with version 1.5.3, Mercurial allows environment variable expansion on path names for sub repositories when creating it or cloning a parent repository, but it doesn't validate whether the final path name outside the repository root directory. An attacker can leverage this weakness using a combination of symbolic links and environment variables to craft a tampered repository, leading Mercurial to write files outside the repository as long the destination location is empty.

This issue affects the versions of mercurial as shipped with Red Hat Enterprise Linux 7. Red Hat Product Security has rated this issue as having a security impact of Moderate. A future update may address this issue. For additional information, refer to the Issue Severity Classification: https://access.redhat.com/security/updates/classification/.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.