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CVE Record

CVE-2020-3535: Cisco Webex Teams Client for Windows DLL Hijacking Vulnerability

A vulnerability in the loading mechanism of specific DLLs in the Cisco Webex Teams client for Windows could allow an authenticated, local attacker to load a malicious library. To exploit this vulnerability, the attacker needs valid credentials on the Windows system. The vulnerability is due to incorrect handling of directory paths at run time. An attacker could exploit this vulnerability by placing a malicious DLL file in a specific location on the targeted system. This file will execute when the vulnerable application launches. A successful exploit could allow the attacker to execute arbitrary code on the targeted system with the privileges of another user’s account.

HighCVSS 7.8Not KEV-listedUpdated
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw affects Cisco Webex Teams on Windows. A local user with valid Windows credentials could make the client load an attacker-controlled library when the app starts, causing code to run as another user account. This is a serious endpoint risk, but the provided sources do not show active exploitation.

Executive priority

Treat as a high-priority endpoint hygiene issue for organizations using Webex Teams on Windows, especially shared workstations or environments with many local users. It is not remotely exploitable based on the provided sources.

Technical view

CVE-2020-3535 is a CWE-427 DLL hijacking issue caused by incorrect runtime directory path handling in Cisco Webex Teams Client for Windows. Exploitation requires authenticated local access. Successful exploitation can execute arbitrary code on the targeted Windows system with another user account’s privileges.

Likely exposure

Exposure is limited to Windows systems running Cisco Webex Teams Client. The provided bundle does not identify affected or fixed version numbers, so teams must verify installed versions against Cisco’s advisory.

Exploitation context

The attacker must already have valid credentials on the Windows system. The source bundle says exploitation involves placing a malicious DLL where the client may load it. KEV is false, and no cited source confirms active exploitation.

Researcher notes

The strongest evidence is Cisco’s advisory and the CVE record. Key gaps are exact affected versions, fixed versions, and any workaround details, which are not included in the source bundle. Do not assume exploitation in the wild without further sourced evidence.

Mitigation direction

  • Review Cisco’s advisory and apply the fixed Webex Teams for Windows release it identifies.
  • Remove unsupported or unneeded Webex Teams installations from Windows endpoints.
  • Limit local user write permissions in application and shared directories.
  • Monitor Webex Teams process launches and unexpected DLL loads.

Validation and detection

  • Inventory Windows endpoints with Cisco Webex Teams installed.
  • Compare installed client versions against Cisco advisory affected and fixed release guidance.
  • Review EDR logs for unexpected DLL loads associated with Webex Teams.
  • Confirm local users cannot write to sensitive application directories.
Prepared
Confidence
medium
Sources
3

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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

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cwe · low confidence lookup

CWE-427: 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.

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description · low confidence lookup

Execution behavior lookup

The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

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cve · low confidence lookup

CVE-2020-3535 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

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.

1CVSS vectors
0Timeline events
0ADP providers
2Source links

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2020-3535Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco Webex Teamsn/aListed
Weakness

CWE details

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-427 · source CWE mapping

Uncontrolled Search Path Element

Uncontrolled Search Path Element represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.