CVE-2026-49958 Hermes WebUI < 0.51.303 TOCTOU Race Condition via git_discard
Attackers can delete arbitrary files outside the workspace by exploiting a race condition in the git_discard function of Hermes WebUI.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- None listed
What is CVE-2026-49958?
CVE-2026-49958 is a medium-severity vulnerability in nesquena hermes-webui, published on 9 Jun 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
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.
Weakness: CWE-367
Which versions are affected by CVE-2026-49958?
How do I fix CVE-2026-49958?
No fix has been published for CVE-2026-49958 yet. Limit exposure of the affected software until one is available.
Is CVE-2026-49958 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49958 exists.
Sources
Also known as GHSA-qg92-vxjm-x4q9.