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CVE-2026-25039NVD status: Deferred

parsec-cloud: Path Traversal: 'UNCsharename' (Windows UNC Share)

Published Updated By the CyberSecBulletin desk

CVE-2026-25039 is a high-severity path traversal: 'uncsharename' (windows UNC share) vulnerability in parsec-cloud from Scille, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected parsec-cloud versions: < 3.3.3-rc.0. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.41% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of parsec-cloud you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Scilleparsec-cloud< 3.3.3-rc.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (github.com).

Official description

Parsec is a cloud-based application for simple and cryptographically secure file sharing. The application does not sanitize the workspace name, creating a vulnerability if that workspace name is a UNC path. When creating mountpoint in the windows filesystem to mount the workspace of an organization, the application does not sanitize the workspace name. The cause issue if the workspace name evaluate to a UNC path since it's allowed for the name to containt `\` char. If the UNC path is invalid (or the targeted resource is not available) the application become unresponsive otherwise the system will interact with the mounted UNC path allowing the attacker to retrieve to [`NTLM`] hash.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Path Traversal: 'UNCsharename' (Windows UNC Share)

The product accepts input that identifies a Windows UNC share ('UNCsharename') that potentially redirects access to an unintended location or arbitrary file.

How developers prevent this class of flaw

  • Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.

More Path Traversal: 'UNCsharename' (Windows UNC Share) vulnerabilities (CWE-40)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in parsec-cloud

All parsec-cloud vulnerabilities

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