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CVE Record

CVE-2021-20491: IBM Spectrum Protect Server 7.1 and 8.1 is subject to a stack-based buffer overflow caused by improper boun...

IBM Spectrum Protect Server 7.1 and 8.1 is subject to a stack-based buffer overflow caused by improper bounds checking during the parsing of commands. By issuing such a command with an improper parameter, an authorized administrator could overflow a buffer and cause the server to crash. IBM X-Force ID: 197792.

MediumCVSS 4.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-20491 is a denial-of-service issue in IBM Spectrum Protect Server 7.1 and 8.1. A highly privileged, authorized administrator could trigger a stack-based buffer overflow while command parameters are parsed, causing the server to crash. The business risk is service disruption, not data theft based on the sources.

Executive priority

Treat this as a moderate operational resilience issue. It can crash a backup platform, but the available evidence requires high privileges and shows no data exposure. Prioritize remediation where Spectrum Protect supports critical recovery workflows or where administrator accounts are weakly controlled.

Technical view

IBM describes improper bounds checking during command parsing, leading to a stack-based buffer overflow. The CVSS 3.0 vector is local, low complexity, high privileges required, no user interaction, high availability impact, and no confidentiality or integrity impact. The listed score is 4.4, medium severity.

Likely exposure

Exposure appears limited to environments running IBM Spectrum Protect Server 7.1 or 8.1 where administrator-level access exists. Internet exposure is not indicated by the CVSS vector, which lists local attack access and high privileges required.

Exploitation context

The source bundle does not show CISA KEV listing, public active exploitation, or exploit maturity beyond CVSS exploit maturity marked unproven. The attacker must already be an authorized administrator, so this is most relevant for insider misuse, compromised admin accounts, or post-compromise disruption.

Researcher notes

The key constraint is privilege: CVSS lists PR:H and AV:L. The described impact is availability-only server crash from stack-based overflow during command parameter parsing. The bundle does not include concrete patched versions, exploit details, or affected CPEs, so validation should stay version- and advisory-driven.

Mitigation direction

  • Review IBM advisory guidance for fixed levels or interim mitigations.
  • Prioritize upgrade planning for any remaining Spectrum Protect Server 7.1 or 8.1 systems.
  • Restrict administrative access to trusted operators and managed hosts.
  • Monitor backup service health and unexpected Spectrum Protect Server crashes.
  • Audit administrator account security, MFA, and privileged access controls.

Validation and detection

  • Inventory IBM Spectrum Protect Server versions in backup and recovery environments.
  • Confirm whether versions 7.1 or 8.1 are present.
  • Check IBM advisory status before choosing upgrade or mitigation actions.
  • Review logs for unexplained server crashes tied to administrative sessions.
  • Verify privileged access controls limit who can issue administrative commands.
Prepared
Confidence
medium
Sources
4

Public sources used

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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CVE-2021-20491 mapping review

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Vulnerability profileCVE Program record
Severity
Medium
CVSS
4.4 (3.0)
Known Exploited
No
Published

Vector: CVSS:3.0/I:N/A:H/UI:N/C:N/S:U/AV:L/AC:L/PR:H/RL:O/E:U/RC:C

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
4.4CVSS 3.0MediumCVSS:3.0/I:N/A:H/UI:N/C:N/S:U/AV:L/AC:L/PR:H/RL:O/E:U/RC:C0.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.0 score

4.4Medium
CVSS 3.0 vector shape for CVE-2021-20491Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.0/I:N/A:H/UI:N/C:N/S:U/AV:L/AC:L/PR:H/RL:O/E:U/RC:C

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
IBMSpectrum Protect Server8.1, 7.1Listed
Weakness

CWE details

No CWE listed

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