What’s Vulnerable › Vulnerabilities

CVE-2026-49958: Hermes WebUI < 0.51.303 TOCTOU Race Condition via git_discard

• Severity: medium (CVSS 5.0 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-06-09 · updated 2026-07-23
• Weakness: CWE-367

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.

Affected products

• nesquena hermes-webui: before 0.51.303 — fixed in 0.51.303

How to fix

Upgrade to a fixed version: nesquena hermes-webui 0.51.303. Check the vendor advisory for mitigations.

References

• https://github.com/nesquena/hermes-webui/commit/4580f584964d640b95c4ffc9245a21ab926bec73
• https://github.com/nesquena/hermes-webui/pull/3702
• https://github.com/nesquena/hermes-webui/pull/3756
• https://github.com/nesquena/hermes-webui/releases/tag/v0.51.303
• https://www.vulncheck.com/advisories/hermes-webui-toctou-race-condition-via-git-discard
• https://github.com/nesquena/hermes-webui/pull/3702

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