CVE-2018-1000132: Critical severity mercurial vulnerability

Quote from release notes:

All versions of Mercurial prior to 4.5.2 have vulnerabilities in the HTTP server that allow permissions bypass to:

Perform writes on repositories that should be read-only Perform reads on repositories that shouldn't allow read access

The nature of the vulnerabilities is:

Wire protocol commands that didn't explicitly declare their permissions had no permissions checking done. The web.{allow-pull, allow-push, denyread, etc} config options governing access control were never consulted when running these commands. This allowed permissions bypass for impacted commands.

The batch wire protocol command did not list its permission requirements nor did it enforce permissions on individual sub-commands.

The implication of these vulnerabilities is that no permissions checking was performed on commands and this could lead to accessing data that web. config options were supposed to prevent access to or modifying data (via wire protocol commands that can mutate data) without authorization. A Mercurial HTTP server in its default configuration is supposed to be read-only. However, a well-crafted batch command could invoke commands that perform writes.

Upstream patch:

https://www.mercurial-scm.org/repo/hg/rev/2ecb0fc535b1

References:

https://www.mercurial-scm.org/wiki/WhatsNew#Mercurial4.5.1.2F4.5.2.282018-03-06.29

— Red Hat