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CVE Record

CVE-2021-1237: Cisco AnyConnect Secure Mobility Client for Windows DLL Injection Vulnerability

A vulnerability in the Network Access Manager and Web Security Agent components of Cisco AnyConnect Secure Mobility Client for Windows could allow an authenticated, local attacker to perform a DLL injection attack. To exploit this vulnerability, the attacker would need to have valid credentials on the Windows system. The vulnerability is due to insufficient validation of resources that are loaded by the application at run time. An attacker could exploit this vulnerability by inserting a configuration file in a specific path in the system which, in turn, causes a malicious DLL file to be loaded when the application starts. A successful exploit could allow the attacker to execute arbitrary code on the affected machine with SYSTEM privileges.

HighCVSS 7.8Not KEV-listedUpdated
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw lets a signed-in local Windows user abuse Cisco AnyConnect components to get SYSTEM-level code execution. It is not a remote internet attack, but it can turn ordinary endpoint access into full machine compromise on affected systems.

Executive priority

Treat as a high-priority endpoint hardening issue, especially in environments where AnyConnect is broadly deployed. The business risk is privilege escalation after initial local access, not direct remote compromise.

Technical view

CVE-2021-1237 affects Cisco AnyConnect Secure Mobility Client for Windows, specifically Network Access Manager and Web Security Agent components. Insufficient validation of runtime-loaded resources can allow DLL injection. CVSS 3.1 is 7.8, CWE-427, with local attack vector, low complexity, low privileges, and no user interaction.

Likely exposure

Exposure is limited to Windows systems running Cisco AnyConnect Secure Mobility Client with the affected components present. The provided sources do not name exact affected or fixed versions, so version exposure must be confirmed against Cisco’s advisory.

Exploitation context

The source describes authenticated local exploitation requiring valid Windows credentials. Successful exploitation can execute arbitrary code with SYSTEM privileges. The CVE is not listed as KEV, and the provided bundle contains no evidence of active exploitation.

Researcher notes

The key technical issue is unsafe runtime resource loading leading to DLL injection, mapped to CWE-427. Public source details are limited; avoid assuming affected versions, patch levels, or exploitation in the wild beyond the Cisco and CVE records.

Mitigation direction

  • Review Cisco’s advisory for affected and fixed release guidance.
  • Inventory Windows AnyConnect deployments and installed components.
  • Apply Cisco-supported updates or workarounds where applicable.
  • Prioritize endpoints used by administrators or privileged users.
  • Monitor endpoint alerts for local privilege escalation behavior.

Validation and detection

  • Confirm whether AnyConnect is installed on Windows endpoints.
  • Check for Network Access Manager or Web Security Agent components.
  • Compare installed versions against Cisco’s advisory.
  • Verify remediation through endpoint inventory after changes.
  • Document systems where exposure cannot yet be determined.
Prepared
Confidence
high
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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-427: Exact CWE lookup

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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-2021-1237 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-2021-1237Attack 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 AnyConnect Secure Mobility Clientn/aListed
Weakness

CWE details

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