CVE-2026-110855 in GitPython
Summary
by MITRE • 10/15/2026
GitPython before 3.2.0 contains an information disclosure vulnerability that allows malicious repositories to expand environment variables via separate_git_dir in Repo._clone(), which omits expand_vars=False when calling Git.polish_url(). Attackers can craft a .gitmodules submodule name containing variable syntax so that clone plus submodule_update exposes secrets in .git/modules directory names and DEBUG logs.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in versions of GitPython prior to 3.2.0 represents a significant information disclosure risk stemming from improper handling of environment variables during repository cloning operations. Specifically, the flaw resides within the Repo._clone() method where the separate_git_dir parameter is utilized without enforcing strict variable expansion controls. When this function invokes Git.polish_url(), it fails to pass expand_vars=False, thereby allowing untrusted input derived from malicious repositories to trigger shell-like environment variable substitution. This architectural oversight permits attackers who control a remote repository or its submodule definitions to inject arbitrary commands that are executed during the cloning process, leading to unintended exposure of sensitive system information.
The operational mechanism of this exploit relies on the manipulation of .gitmodules files within a crafted repository. An attacker can define a submodule name containing specific variable syntax designed to reference environment variables such as PATH, HOME, or other secret-containing fields. When a victim application utilizes GitPython to clone such a repository and subsequently executes submodule_update(), the library processes these malicious names through the vulnerable code path. Because expand_vars is not disabled during URL polishing, the system attempts to resolve these variable references against the local environment of the executing process. This results in the substitution of actual secret values into the resulting file paths or log entries rather than treating them as literal strings.
The impact of this vulnerability extends beyond simple data leakage within application logs. The primary consequence is the exposure of secrets embedded in .git/modules directory names and DEBUG level logging outputs generated by GitPython itself. Since these operations often occur during automated build pipelines, continuous integration workflows, or developer workstations where sensitive credentials are present in environment variables, the risk profile is elevated significantly. Attackers do not need to execute arbitrary code on the target system but can instead passively harvest high-value secrets simply by inducing a clone operation against their malicious repository. This aligns with CWE-200, which classifies this as an Information Exposure vulnerability, and maps to MITRE ATT&CK technique T1537, involving communication through file shares or directories for data exfiltration purposes via indirect means.
Mitigation strategies must focus on immediate version updates and defensive coding practices within applications relying on GitPython. The most effective remediation is upgrading the library to version 3.2.0 or later, where this specific logic flaw has been addressed by ensuring that environment variable expansion is strictly disabled during URL polishing operations regardless of input context. For organizations unable to upgrade immediately due to dependency constraints, implementing a wrapper around the GitPython API can provide temporary protection. This wrapper should explicitly sanitize submodule names and repository URLs before passing them to clone functions, stripping out any characters commonly associated with shell variable syntax such as dollar signs or curly braces. Additionally, enabling strict logging filters that redact potential secret patterns from DEBUG logs can mitigate the secondary impact of information leakage through log files while longer-term architectural changes are implemented.