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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.

PUBLISHED Reserved 2026-06-02 | Published 2026-06-09 | Updated 2026-06-09 | Assigner VulnCheck




MEDIUM: 4.3CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:A/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N

MEDIUM: 5.0CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:N/I:L/A:H

Problem types

Time-of-check Time-of-use (TOCTOU) Race Condition

Product status

Default status
affected

Any version before 0.51.303
affected

Credits

Chia Min Jun Lennon finder

References

github.com/nesquena/hermes-webui/pull/3702 exploit

github.com/nesquena/hermes-webui/releases/tag/v0.51.303 release-notes

github.com/nesquena/hermes-webui/pull/3702 technical-description

github.com/nesquena/hermes-webui/pull/3756 issue-tracking

github.com/...ommit/4580f584964d640b95c4ffc9245a21ab926bec73 patch

www.vulncheck.com/...i-toctou-race-condition-via-git-discard third-party-advisory

cve.org (CVE-2026-49958)

nvd.nist.gov (CVE-2026-49958)

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