Which versions of Hermes WebUI are affected by CVE-2026-6832?

Hermes WebUI contains a vulnerability allowing authenticated users to delete arbitrary JSON files on hosting systems through improper path validation in the session deletion endpoint.. A patch is available.

How to fix or mitigate CVE-2026-6832?

Within 24 hours, identify all Hermes WebUI instances and document their versions to assess exposure. Within 7 days, consult the vendor advisory to obtain the patched version (fixes for PR #409 are available) and apply across all instances. Within 30 days, audit file systems for any unauthorized deletions, review authentication controls to restrict the affected endpoint to trusted users only, and implement input validation monitoring.

Hermes WebUI CVE-2026-6832

Q: What is the CVSS score of CVE-2026-6832?

CVE-2026-6832 has a CVSS 4.0 base score of 7.2 (High). CVSS vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X. EPSS exploitation probability: 0.1%.

EUVD-2026-24517 HIGH

Path Traversal (CWE-22)

2026-04-21 VulnCheck

Path Traversal Hermes Webui Nesquena

7.2

CVSS 4.0 · NVD

Severity by source

NVD PRIMARY

7.2 HIGH

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

vuln.today AI

8.1 HIGH

Remote, low-complexity, but requires low-privilege authentication (PR:L); delete-only primitive gives no confidentiality (C:N) yet high integrity and availability impact (I:H/A:H).

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

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

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Lifecycle Timeline

Source Code Evidence Fetched

Jul 24, 2026 - 05:30 vuln.today

Analysis Generated

Jul 24, 2026 - 05:30 vuln.today

CVSS changed

Apr 21, 2026 - 22:22 NVD

8.1 (HIGH) 7.2 (HIGH)

EUVD ID Assigned

Apr 21, 2026 - 22:16 euvd

EUVD-2026-24517

Patch released

Apr 21, 2026 - 22:16 nvd

Patch available

CVE Published

Apr 21, 2026 - 21:44 nvd

HIGH 7.2

DescriptionCVE.org

Hermes WebUI contains an arbitrary file deletion vulnerability in the /api/session/delete endpoint that allows authenticated attackers to delete files outside the session directory by supplying an absolute path or path traversal payload in the session_id parameter. Attackers can exploit unvalidated session identifiers to construct paths that bypass the SESSION_DIR boundary and delete writable JSON files on the host system.

AnalysisAI

Arbitrary file deletion in Hermes WebUI (nesquena/hermes-webui, all versions prior to the PR #409 fix) allows an authenticated attacker to delete arbitrary writable JSON files on the host by supplying an absolute path or path-traversal sequence in the session_id parameter of the /api/session/delete endpoint. Because the endpoint concatenates the unvalidated identifier onto SESSION_DIR without canonicalization, an attacker can escape the intended session directory and destroy files outside it. Publicly available exploit code exists (VulnCheck advisory and upstream regression tests demonstrate the payloads), but it is not listed in CISA KEV and EPSS is low (0.09%, 26th percentile), indicating no evidence of widespread automated exploitation.

Technical ContextAI

The vulnerability is a classic CWE-22 path traversal in a Python-based web UI. In api/routes.py the delete handler built the target path as SESSION_DIR / f"{sid}.json" using the client-supplied session_id directly, with no allow-list validation or canonical-path containment check. Python's pathlib treats an absolute path on the right side of the / operator as replacing the base entirely, and it does not collapse ../ segments, so both an absolute path (e.g. /etc/something) and a ../../../ traversal payload resolve outside SESSION_DIR. The upstream fix adds two defenses: a strict character allow-list restricting sid to [0-9a-z_], and a canonicalization check that calls .resolve() on the constructed path and then .relative_to(SESSION_DIR.resolve()), rejecting anything that escapes the boundary. CPE cpe:2.3:a:nesquena:hermes-webui identifies the single affected product.

RemediationAI

Vendor-released patch: upgrade to Hermes WebUI v0.50.132 (or the v0.50.32 tagged release), which incorporate the fix from pull request https://github.com/nesquena/hermes-webui/pull/409 (with follow-up https://github.com/nesquena/hermes-webui/pull/412 and commit 3cc5839bf303fa6758bfdac538507407a2929655). The fix adds a strict [0-9a-z_] character allow-list on session_id plus a canonical-path containment check (resolve() followed by relative_to(SESSION_DIR)). If you cannot upgrade immediately, restrict network access to the /api/session/delete endpoint and to the Hermes WebUI service generally (place it behind authenticated reverse-proxy access controls or bind it to localhost), which prevents remote reach at the cost of limiting legitimate remote use; additionally, run the service under a low-privilege account whose write access is confined to the session directory so that traversal payloads cannot reach sensitive files elsewhere on the host (trade-off: may require adjusting file ownership for other application data). Consult the VulnCheck advisory at https://www.vulncheck.com/advisories/nesquena-hermes-webui-arbitrary-file-deletion-via-unvalidated-session-id for details.