CVE-2018-17983 in Mercurial
Summary
by MITRE
cext/manifest.c in Mercurial before 4.7.2 has an out-of-bounds read during parsing of a malformed manifest entry.
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Analysis
by VulDB Data Team • 03/29/2020
The vulnerability identified as CVE-2018-17983 affects Mercurial version 4.7.2 and earlier, specifically within the cext/manifest.c component. This issue manifests as an out-of-bounds read condition that occurs during the parsing of malformed manifest entries, representing a critical security flaw that could be exploited to disrupt system operations or potentially enable further attack vectors. The vulnerability resides in the core manifest parsing functionality that Mercurial uses to manage repository metadata and file tracking information.
The technical flaw stems from inadequate input validation within the manifest parsing routine where the software fails to properly bounds-check array accesses when processing malformed data structures. This out-of-bounds read vulnerability allows an attacker to craft specially crafted manifest entries that cause the application to access memory locations beyond the intended buffer boundaries. Such behavior typically results in undefined behavior including application crashes, memory corruption, or potentially arbitrary code execution depending on the specific memory access patterns and system configuration. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions that can lead to memory corruption and system instability.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a potential pathway for more sophisticated attacks. When exploited, the out-of-bounds read can cause Mercurial to crash or behave unpredictably, disrupting version control operations and potentially providing attackers with opportunities to gain additional system access. The vulnerability affects any system running affected Mercurial versions and is particularly concerning in environments where Mercurial is used for critical code management and collaboration workflows. Attackers could leverage this vulnerability to cause service disruption or potentially escalate privileges if the application runs with elevated permissions.
Mitigation strategies for CVE-2018-17983 primarily focus on immediate patching of affected Mercurial installations to version 4.7.2 or later, which contains the necessary fixes to address the bounds-checking issues in manifest parsing. Organizations should conduct comprehensive vulnerability assessments to identify all systems running affected Mercurial versions and prioritize remediation efforts accordingly. Additionally, implementing proper input validation and sanitization measures can help reduce the attack surface, while network segmentation and access controls can limit potential exploitation opportunities. The vulnerability demonstrates the importance of maintaining up-to-date software versions and implementing robust security practices in version control systems that handle sensitive code repositories and development workflows.