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ZeptoClaw: Path boundary checks bypass via symlink, TOCTOU, and hardlink

High severity GitHub Reviewed Published Mar 11, 2026 in qhkm/zeptoclaw • Updated Mar 13, 2026

Package

cargo zeptoclaw (Rust)

Affected versions

<= 0.7.5

Patched versions

0.7.6

Description

Summary

Workspace boundary enforcement currently has three related bypass risks. This issue tracks fixing all three in one pull request.

Details

R1 - Dangling Symlink Component Bypass

  • What happens: Path validation can miss dangling symlink components during traversal checks.
  • Why it matters: A symlink that is unresolved at validation time can later resolve to an external location.
  • Impact: Read and write operations may escape workspace boundaries.
  • Affected area: src/security/path.rs (check_symlink_escape).

R2 - TOCTOU Between Validation and Use

  • What happens: The path is validated first, then used later for filesystem operations.
  • Why it matters: A concurrent filesystem change can swap path components after validation but before open/write.
  • Impact: Race-based workspace escape is possible.
  • Affected area: Filesystem and file-consuming tools that call validate_path_in_workspace before I/O.

R3 - Hardlink Alias Bypass

  • What happens: A file inside workspace can be a hardlink to an inode outside the intended workspace trust boundary.
  • Why it matters: Prefix and symlink checks can pass while data access still mutates or reads external content.
  • Impact: Policy bypass for read/write operations.
  • Affected area: Any tool that reads or writes via validated paths.

Risk Matrix

ID Risk Severity Likelihood Impact
R1 Dangling symlink component bypass High Medium Workspace boundary escape for read/write
R2 Validate/use TOCTOU race High Medium Race-based boundary escape during file I/O
R3 Hardlink alias bypass Medium Low-Medium External inode read/write through in-workspace path

PoC

R1 - Dangling symlink component bypass

  1. Create a symlink inside workspace pointing to a missing target.
  2. Validate a path traversing that symlink.
  3. Create the target directory outside workspace after validation.
  4. Perform file operation and observe potential boundary escape if not fail-closed.

R2 - TOCTOU between validation and use

  1. Validate a candidate in-workspace path.
  2. Before open/write, replace an intermediate component with a link to external location.
  3. Continue with the file operation.
  4. Observe boundary escape if operation trusts only stale validation result.

R3 - Hardlink alias bypass

  1. Place a hardlink inside workspace that points to an external inode.
  2. Validate the in-workspace hardlink path.
  3. Read or write through this path.
  4. Observe external inode access through a path that appears in-scope.

Impacts

Unauthorized cross path boundary

Credit

@zpbrent

Patch

f50c17e11ae3e2d40c96730abac41974ef2ee2a8

References

@qhkm qhkm published to qhkm/zeptoclaw Mar 11, 2026
Published to the GitHub Advisory Database Mar 12, 2026
Reviewed Mar 12, 2026
Published by the National Vulnerability Database Mar 12, 2026
Last updated Mar 13, 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 High
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:H/VA:N/SC:N/SI:N/SA:N/E:P

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(22nd percentile)

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.

UNIX Hard Link

The product, when opening a file or directory, does not sufficiently account for when the name is associated with a hard link to a target that is outside of the intended control sphere. This could allow an attacker to cause the product to operate on unauthorized files. Learn more on MITRE.

CVE ID

CVE-2026-32232

GHSA ID

GHSA-2m67-cxxq-c3h8

Source code

Credits

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