Security readout for executives and security teams
Plain-English summary
Velneo vClient 28.1.3 could let someone impersonate a user if they already know that user’s username and hashed password. That can expose confidential data or allow unauthorized changes as the victim. The available bundle does not show active exploitation, but the impact is serious for organizations still using the affected client/server combination.
Executive priority
Handle as a high-priority legacy exposure check. The issue requires prior hash knowledge, but successful abuse can undermine user identity and data integrity. Organizations using Velneo should quickly confirm whether 28.1.3 remains in use and follow vendor guidance.
Technical view
CVE-2021-45036 is an improper authentication issue, CWE-290, in Velneo vClient 28.1.3. The CVSS 3.1 score is 8.7 with network attack vector, high complexity, no privileges, no user interaction, changed scope, high confidentiality and integrity impact, and no availability impact.
Likely exposure
Exposure is likely limited to environments running Velneo vClient 28.1.3 where an attacker can reach the Velneo server path and has obtained a victim username and hashed password. The bundle marks other versions as unaffected by default, but local inventory should confirm deployed versions.
Exploitation context
The source bundle does not identify KEV listing, active exploitation, or public exploit availability. Exploitation is constrained by the need to know the victim’s username and hashed password, but CVSS still rates the issue high because successful abuse can impersonate the victim remotely without user interaction.
Researcher notes
Available evidence identifies the vulnerable product/version and attack precondition, but does not include protocol internals or a detailed patch note in the bundle. Avoid assuming broader Velneo product exposure. Focus validation on version inventory, authentication controls, and vendor-documented Velneo 32 security changes.
Mitigation direction
- Inventory Velneo vClient deployments and identify any version 28.1.3 usage.
- Review INCIBE and Velneo guidance for the supported corrective upgrade path.
- Prioritize vendor-recommended updates related to Velneo 32 authentication validation improvements.
- Restrict Velneo server access to trusted networks where operationally possible.
- Treat exposed password hashes as credential compromise and follow vendor credential guidance.
Validation and detection
- Confirm Velneo vClient version on endpoints that connect to Velneo vServer.
- Check whether any users still operate Velneo vClient 28.1.3.
- Review authentication logs for unexplained sessions using legitimate user identities.
- Verify Velneo server connection settings against current vendor documentation.
- Document whether Velneo 32 security validation changes are deployed.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-290: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-45036 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.7 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N2.25.8Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.7HighVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.incibe.es/en/incibe-cert/notices/aviso/velneo-vclient-improper-authentication-0CVE reference
- https://www.velneo.com/blog/disponible-la-nueva-version-velneo-32CVE reference
- https://doc.velneo.com/v/32/velneo/notas-de-la-version#mejoras-de-seguridad-en-validacion-de-usuario-y-contrasenaCVE reference
- https://velneo.es/mivelneo/listado-de-cambios-velneo-32/CVE reference
- https://doc.velneo.com/v/32/velneo-vserver/funcionalidades/protocolo-vatpsCVE reference
- https://doc.velneo.com/v/32/velneo/funcionalidades-comunes/conexion-con-velneo-vserverCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Authentication Bypass by Spoofing
Authentication Bypass by Spoofing represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.