# 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.

- **Severity:** Medium 4.3 (`CVSS:4.0/AV:L/AC:H/AT:N/PR:L/UI:A/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **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 available:** No
- **Published:** 9 Jun 2026
- **Updated:** 14 Jul 2026
- **Also known as:** GHSA-qg92-vxjm-x4q9

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

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-49958 and fix it if it is affected.

What it is: 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.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-49958 exists.

Affected product: nesquena hermes-webui. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-49958/ (Markdown: https://insights.sbomify.com/CVE-2026-49958/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-49958
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-49958
- OSV: https://osv.dev/vulnerability/CVE-2026-49958

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-49958/
Summaries are generated and may contain mistakes; the official description above is the record.