CVE-2016-9645 in Ikiwiki
Summary
by MITRE
The fix for ikiwiki for CVE-2016-10026 was incomplete resulting in editing restriction bypass for git revert when using git versions older than 2.8.0. This has been fixed in 3.20161229.
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Analysis
by VulDB Data Team • 01/23/2020
The vulnerability described in CVE-2016-9645 represents a critical security flaw in the ikiwiki content management system that emerged from an incomplete remediation effort for a previous vulnerability. This issue specifically affects users operating git version 2.8.0 or older, where the security patch implemented for CVE-2016-10026 failed to fully address all potential attack vectors. The flaw manifests as an editing restriction bypass mechanism that allows unauthorized users to perform git revert operations despite having appropriate access controls in place, creating a significant escalation of privileges within the system.
The technical root cause of this vulnerability lies in the inadequate implementation of access control checks within ikiwiki's git integration functionality. When git versions older than 2.8.0 are used, the system fails to properly validate user permissions during revert operations, allowing malicious actors to circumvent intended editing restrictions. This bypass occurs because the original fix for CVE-2016-10026 did not account for the specific behavioral differences in older git versions, particularly regarding how they handle revert operations and permission validation. The vulnerability operates at the intersection of version control system security and web application access control, creating a complex attack surface that exploits the gap between different git implementation behaviors.
The operational impact of this vulnerability extends beyond simple unauthorized access, as it enables attackers to potentially modify or corrupt content within the ikiwiki system. This bypass allows malicious users to perform git revert operations that should be restricted to authorized personnel, potentially undoing legitimate changes or introducing malicious modifications to the repository. The vulnerability particularly affects collaborative environments where content management systems rely on git for version control, as it undermines the integrity of the content management workflow and could lead to data corruption or unauthorized modifications that might go undetected for extended periods.
Security professionals should note that this vulnerability aligns with CWE-284 Access Control Bypass and represents a classic case of incomplete remediation that leaves systems vulnerable to exploitation. The issue demonstrates how security patches, if not thoroughly tested across different versions of underlying dependencies, can create new attack vectors. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and could be leveraged in combination with other attack vectors to establish persistent access within affected systems. The recommended mitigation strategy involves upgrading to ikiwiki version 3.20161229 or later, which contains the complete fix for this issue, along with ensuring that git installations are updated to versions 2.8.0 or newer to eliminate the underlying compatibility issues that enable the bypass. Organizations should also conduct thorough testing of their ikiwiki environments to verify that all access controls are functioning properly and consider implementing additional monitoring mechanisms to detect unauthorized revert operations.