CVE-2018-1000132

Vulnerability

Mercurial version 4.5 and earlier contains an Incorrect Access Control (CWE-285) vulnerability in the Protocol server [2]. This flaw allows an attacker to bypass intended access restrictions and access data without proper authorization. The vulnerability is present in all versions up to and including 4.5, and it is fixed in version 4.5.1 [1][2].

Exploitation

The attack is exploitable via network connectivity [2]. An attacker can send specially crafted requests to the Protocol server to leverage the incorrect access control, without requiring prior authentication or elevated privileges. Network access to the Mercurial service is the only prerequisite.

Impact

Successful exploitation results in unauthorized data access [2]. The attacker can retrieve sensitive information stored in the Mercurial repository that should be protected by access controls. This constitutes a confidentiality breach, potentially exposing private source code, credentials, or other sensitive data.

Mitigation

The vulnerability is fixed in Mercurial version 4.5.1 [1][2]. Users should upgrade to this version or later immediately. Red Hat Enterprise Linux users can also apply the patch via RHSA-2019:2276 [1]. No other workarounds are specified. The vulnerability is not listed on CISA's Known Exploited Vulnerabilities catalog.