nesquena hermes-webui up to 0.51.302 api/workspace_git.py safe_resolve_ws toctou

Summaryinfo

A vulnerability identified as problematic has been detected in nesquena hermes-webui up to 0.51.302. Affected by this vulnerability is the function safe_resolve_ws of the file api/workspace_git.py. The manipulation leads to toctou. This vulnerability is referenced as CVE-2026-49958. The attack can only be performed from a local environment. No exploit is available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in nesquena hermes-webui up to 0.51.302. This issue affects the function safe_resolve_ws of the file api/workspace_git.py. The manipulation with an unknown input leads to a toctou vulnerability. Using CWE to declare the problem leads to CWE-367. The product checks the state of a resource before using that resource, but the resource's state can change between the check and the use in a way that invalidates the results of the check. This can cause the product to perform invalid actions when the resource is in an unexpected state. Impacted is integrity, and availability. The summary by CVE is:

Hermes WebUI before version 0.51.303 contains a time-of-check time-of-use (TOCTOU) race condition vulnerability in the git_discard function within api/workspace_git.py that allows attackers to delete files outside the configured workspace boundary by replacing a validated path component with a symlink after validation but before deletion. Attackers can substitute a workspace-controlled path component with a symlink pointing to an external directory between the safe_resolve_ws() validation step and the subsequent Path.unlink() or shutil.rmtree() deletion call, causing the delete operation to follow the symlink and remove arbitrary files outside the workspace.

The weakness was published by Chia Min Jun Lennon. It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-49958 since 06/02/2026. The exploitation is known to be difficult. Attacking locally is a requirement. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 0.51.303 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 4580f584964d640b95c4ffc9245a21ab926bec73 is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Vendor

• nesquena

Name

• hermes-webui

Version

• 0.51.302

License

• open-source

Website

• Product: https://github.com/nesquena/hermes-webui/

CPE 2.3info

• 🔒

CPE 2.2info

• 🔒

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