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CVE Record

CVE-2021-1572: ConfD CLI Secure Shell Server Privilege Escalation Vulnerability

A vulnerability in ConfD could allow an authenticated, local attacker to execute arbitrary commands at the level of the account under which ConfD is running, which is commonly root. To exploit this vulnerability, an attacker must have a valid account on an affected device. The vulnerability exists because the affected software incorrectly runs the SFTP user service at the privilege level of the account that was running when the ConfD built-in Secure Shell (SSH) server for CLI was enabled. If the ConfD built-in SSH server was not enabled, the device is not affected by this vulnerability. An attacker with low-level privileges could exploit this vulnerability by authenticating to an affected device and issuing a series of commands at the SFTP interface. A successful exploit could allow the attacker to elevate privileges to the level of the account under which ConfD is running, which is commonly root. Note: Any user who can authenticate to the built-in SSH server may exploit this vulnerability. By default, all ConfD users have this access if the server is enabled. Software updates that address this vulnerability have been released.

HighCVSS 7.8Not KEV-listedUpdated
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-1572 lets a logged-in low-privilege user potentially gain the privileges of the ConfD process, commonly root. The issue matters only when the ConfD built-in SSH server for CLI is enabled. Cisco states software updates are available.

Executive priority

Prioritize remediation for systems where ConfD CLI SSH is enabled, especially production or privileged management environments. This is not remotely exploitable without credentials, but successful abuse can produce root-level impact.

Technical view

The flaw is a privilege management issue in Cisco ConfD. The SFTP user service can run with the privilege level of the account active when the built-in CLI SSH server was enabled. An authenticated local user may escalate to that ConfD runtime account.

Likely exposure

Exposure is limited to affected Cisco ConfD deployments where the built-in SSH server for CLI is enabled and a user can authenticate. Cisco says devices without that built-in SSH server enabled are not affected.

Exploitation context

The source bundle does not show CISA KEV listing or cited evidence of active exploitation. Exploitation requires valid account access, low privileges, no user interaction, and local access according to the CVSS vector.

Researcher notes

Mapped to CWE-266 with CVSS 3.1 score 7.8: AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Key validation is the built-in SSH server state and authenticated user access. Fixed version details require Cisco advisory review.

Mitigation direction

  • Apply Cisco software updates that address CVE-2021-1572.
  • Review Cisco ConfD and NSO advisories for fixed-release guidance.
  • Disable ConfD built-in CLI SSH where it is not required, following vendor guidance.
  • Limit who can authenticate to the built-in SSH server until patched.

Validation and detection

  • Inventory systems using Cisco ConfD and relevant Cisco NSO deployments.
  • Verify whether the ConfD built-in SSH server for CLI is enabled.
  • Check installed versions against Cisco advisory fixed-release guidance.
  • Identify low-privileged users who can authenticate to the built-in SSH server.
  • Confirm updates or configuration changes remove the exposure condition.
Prepared
Confidence
high
Sources
4

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-266: 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

Privilege behavior lookup

The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. 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-2021-1572 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
3Source 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-2021-1572Attack 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
Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco ConfDn/aListed
Weakness

CWE details

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