Security readout for executives and security teams
Plain-English summary
CVE-2021-1592 is a Cisco UCS Manager availability issue. A logged-in remote user could create many SSH sessions and cause internal UCS Manager processes to crash and restart, temporarily blocking CLI and web UI access. It does not affect confidentiality or integrity in the provided sources.
Executive priority
Treat this as a moderate operational resilience issue. Prioritize exposed or shared-administrator UCS Manager environments because management-plane interruption can delay infrastructure operations, even though the vulnerability requires credentials and has limited availability impact.
Technical view
Cisco describes improper resource management for established SSH sessions in Cisco UCS Manager Software. The issue is network-reachable, low complexity, requires valid credentials, and can produce limited availability impact. The CVSS v3.1 score is 4.3 with CWE-664 listed.
Likely exposure
Exposure is mainly Cisco UCS Manager environments where authenticated users can reach SSH on the management interface. The provided bundle lists Cisco Unified Computing System managed deployments but does not provide affected version ranges.
Exploitation context
The bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires valid user credentials and the ability to establish many SSH sessions. The expected result is temporary management-plane disruption, not data theft or code execution.
Researcher notes
Evidence supports an authenticated SSH session resource-management DoS only. The provided sources do not name affected version ranges, fixed releases, workarounds, or exploit-in-the-wild activity. Avoid expanding impact beyond temporary CLI and web UI access loss.
Mitigation direction
- Check Cisco’s advisory for affected releases and fixed software guidance.
- Restrict UCS Manager SSH access to authorized administrative networks.
- Review and remove unnecessary UCS Manager user credentials.
- Monitor UCS Manager for excessive SSH sessions and process restarts.
Validation and detection
- Inventory Cisco UCS Manager deployments and installed software versions.
- Confirm whether SSH management access is exposed beyond trusted administrators.
- Review authentication logs for unusual SSH session volume.
- Check operational logs for UCS Manager process crashes or restarts.
- Compare each deployment against Cisco’s advisory guidance.
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-664: 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 lookupCVE-2021-1592 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
- Medium
- CVSS
- 4.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
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:L/PR:L/UI:N/S:U/C:N/I:N/A:L2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
4.3MediumVector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- 20210825 Cisco UCS Manager Software SSH Sessions Denial of Service VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
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.
Improper Control of a Resource Through its Lifetime
Improper Control of a Resource Through its Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.