CVE-2021-1592Network attack vector

Authenticated management outage via SSH session exhaustion

Published Aug 25, 2021 · Updated Nov 7, 2024

Denial of service in Cisco UCS Manager 4.0 and 4.1 allows remote authenticated users to interrupt management access through SSH. The SSH session handler improperly manages resources for established sessions, so opening a significant number crashes and restarts internal management processes. Valid credentials are required; exploitation temporarily removes CLI and web UI access without reported data compromise.

CVSS severity4.3
Medium
EPSS probability1.03%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco UCS Manager 4.0 and 4.1 allows remote authenticated users to interrupt management access through SSH. The SSH session handler improperly manages resources for established sessions, so opening a significant number crashes and restarts internal management processes. Valid credentials are required; exploitation temporarily removes CLI and web UI access without reported data compromise.

The record

CVE
CVE-2021-1592
Published
Aug 25, 2021
Updated
Nov 7, 2024
Vendor
ClamAV
Product
Cisco Unified Computing System (Managed)
Classifications
CWE-770, CWE-664, T1499.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 7, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

ClamAV · Cisco Unified Computing System (Managed)version=n/a

Published CVSS scores

4.3Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L/E:X/RL:X/RC:X
4.0NISTAV:N/AC:L/Au:S/C:N/I:N/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-664Improper Control of a Resource Through its Lifetime
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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