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gix and gitoxide's symlinked .gitmodules are followed and parsed from outside of the repository

High severity GitHub Reviewed Published Apr 25, 2026 in GitoxideLabs/gitoxide

Package

cargo gitoxide (Rust)

Affected versions

<= 0.52.0

Patched versions

0.52.1
cargo gix (Rust)
< 0.83.0
0.83.0

Description

Summary

attachments:
pocs.zip

When Repository::submodules() loads submodule metadata, it prefers the worktree .gitmodules file if that path exists. In the current implementation, the path is read with std::fs::read(), which follows symlinks. As a result, a repository can present a symlinked .gitmodules that points outside the repository, and gitoxide will parse the out-of-repository bytes as submodule configuration.

This is a repository-boundary violation. A caller using the high-level submodule API can believe it is reading repository-local submodule metadata, while the bytes are actually coming from an arbitrary file outside the repository tree.

Root cause analysis

The relevant flow is:

  1. gix/src/repository/location.rs derives the worktree .gitmodules path as workdir/.gitmodules.
  2. gix/src/repository/submodule.rs reads that path with std::fs::read(&path) and immediately parses the bytes as a submodule configuration file.
  3. Repository::submodules() exposes the parsed entries through the high-level API.

The issue is not in the parser. The issue is that the worktree path is treated as an ordinary file without checking whether it is a symlink, and without checking whether the canonicalized target remains inside the repository worktree.

Because std::fs::read() follows symlinks, a malicious repository can cause gitoxide to ingest bytes from an attacker-chosen location outside the repository. The resulting Submodule objects then expose name, path, and url values derived from that external file.

Reproduction steps

Use the attached PoC zip that contains the pocs/ workspace.

  1. Unzip the PoC archive.

  2. Enter pocs/F001.

  3. Run:

    cargo run --quiet

  4. Compare the output with pocs/F001/result.txt.

Important outputs include:

  • gitmodules_symlink=.../victim-repo/.gitmodules
  • symlink_target=.../outside/modules.conf
  • parsed_name=symlinked
  • parsed_path=deps/symlinked
  • parsed_url=https://attacker.example/symlinked.git

These outputs show that gitoxide parsed the submodule configuration from the symlink target outside the repository, not from repository-local bytes.

Impact

Confirmed impact:

  • out-of-repository bytes can be injected into the result of Repository::submodules();
  • callers can be misled about submodule metadata such as name, path, and url;
  • any downstream workflow that uses those values to decide clone, fetch, update, or policy behavior is operating on attacker-controlled data that did not actually originate from the repository tree.

This report does not claim direct command execution from this code path by itself. The demonstrated impact is metadata injection across the repository boundary.

Recommended fix

A safe fix is to stop silently following symlinks for the worktree .gitmodules path in this loading path.

Reasonable options include:

  1. use symlink_metadata() / lstatstyle checks and reject symlinked .gitmodules when loading from the worktree;
  2. canonicalize the target and verify that it still resides under the repository worktree before reading it;
  3. for security-sensitive callers, prefer loading .gitmodules from the index or HEAD tree rather than following the worktree path.

At minimum, the worktree path should not silently follow symlinks to arbitrary external files.

References

@Byron Byron published to GitoxideLabs/gitoxide Apr 25, 2026
Published to the GitHub Advisory Database May 5, 2026
Reviewed May 5, 2026

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v4 base metrics

Exploitability Metrics
Attack Vector Network
Attack Complexity Low
Attack Requirements None
Privileges Required None
User interaction None
Vulnerable System Impact Metrics
Confidentiality High
Integrity None
Availability None
Subsequent System Impact Metrics
Confidentiality None
Integrity None
Availability None

CVSS v4 base metrics

Exploitability Metrics
Attack Vector: This metric reflects the context by which vulnerability exploitation is possible. This metric value (and consequently the resulting severity) will be larger the more remote (logically, and physically) an attacker can be in order to exploit the vulnerable system. The assumption is that the number of potential attackers for a vulnerability that could be exploited from across a network is larger than the number of potential attackers that could exploit a vulnerability requiring physical access to a device, and therefore warrants a greater severity.
Attack Complexity: This metric captures measurable actions that must be taken by the attacker to actively evade or circumvent existing built-in security-enhancing conditions in order to obtain a working exploit. These are conditions whose primary purpose is to increase security and/or increase exploit engineering complexity. A vulnerability exploitable without a target-specific variable has a lower complexity than a vulnerability that would require non-trivial customization. This metric is meant to capture security mechanisms utilized by the vulnerable system.
Attack Requirements: This metric captures the prerequisite deployment and execution conditions or variables of the vulnerable system that enable the attack. These differ from security-enhancing techniques/technologies (ref Attack Complexity) as the primary purpose of these conditions is not to explicitly mitigate attacks, but rather, emerge naturally as a consequence of the deployment and execution of the vulnerable system.
Privileges Required: This metric describes the level of privileges an attacker must possess prior to successfully exploiting the vulnerability. The method by which the attacker obtains privileged credentials prior to the attack (e.g., free trial accounts), is outside the scope of this metric. Generally, self-service provisioned accounts do not constitute a privilege requirement if the attacker can grant themselves privileges as part of the attack.
User interaction: This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable system. This metric determines whether the vulnerability can be exploited solely at the will of the attacker, or whether a separate user (or user-initiated process) must participate in some manner.
Vulnerable System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the VULNERABLE SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the VULNERABLE SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the VULNERABLE SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
Subsequent System Impact Metrics
Confidentiality: This metric measures the impact to the confidentiality of the information managed by the SUBSEQUENT SYSTEM due to a successfully exploited vulnerability. Confidentiality refers to limiting information access and disclosure to only authorized users, as well as preventing access by, or disclosure to, unauthorized ones.
Integrity: This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. Integrity of the SUBSEQUENT SYSTEM is impacted when an attacker makes unauthorized modification of system data. Integrity is also impacted when a system user can repudiate critical actions taken in the context of the system (e.g. due to insufficient logging).
Availability: This metric measures the impact to the availability of the SUBSEQUENT SYSTEM resulting from a successfully exploited vulnerability. While the Confidentiality and Integrity impact metrics apply to the loss of confidentiality or integrity of data (e.g., information, files) used by the system, this metric refers to the loss of availability of the impacted system itself, such as a networked service (e.g., web, database, email). Since availability refers to the accessibility of information resources, attacks that consume network bandwidth, processor cycles, or disk space all impact the availability of a system.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

EPSS score

Weaknesses

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. Learn more on MITRE.

CVE ID

No known CVE

GHSA ID

GHSA-pg4w-g64p-qwhj

Source code

Credits

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