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CVE Record

CVE-2021-33135: Uncontrolled resource consumption in the Linux kernel drivers for Intel(R) SGX may allow an authenticated u...

Uncontrolled resource consumption in the Linux kernel drivers for Intel(R) SGX may allow an authenticated user to potentially enable denial of service via local access.

MediumCVSS 5.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-33135 is a local denial-of-service issue in Linux kernel drivers for Intel SGX. An authenticated local user may consume resources and affect system availability. The provided sources do not indicate data theft or tampering impact.

Executive priority

Treat this as a moderate availability risk. It is not described as remotely exploitable, but it can matter on shared Linux infrastructure or systems supporting SGX-dependent workloads.

Technical view

The CVE describes CWE-400 uncontrolled resource consumption in Linux kernel drivers for Intel(R) SGX. CVSS 3.1 is 5.5: local attack vector, low complexity, low privileges, no user interaction, and high availability impact only.

Likely exposure

Exposure is most likely on Linux systems using Intel SGX drivers where untrusted or lower-privileged local users can access the affected functionality. The bundle does not list exact affected versions, so validate against Intel advisory INTEL-SA-00603 and OS vendor kernel guidance.

Exploitation context

The source bundle marks CISA KEV as false and provides no cited evidence of active exploitation. The realistic concern is local availability disruption by an authenticated user, not remote compromise.

Researcher notes

Evidence is limited to the CVE metadata and Intel advisory reference. Exact affected versions, patch identifiers, and practical exploit conditions are not present in the bundle, so avoid broad product claims until vendor advisories are checked.

Mitigation direction

  • Review Intel advisory INTEL-SA-00603 for affected SGX driver guidance.
  • Check Linux distribution kernel advisories for matching SGX driver updates.
  • Prioritize systems running SGX workloads with multi-user local access.
  • Restrict local access to SGX-capable systems where operationally feasible.
  • Follow vendor guidance before changing SGX configuration or drivers.

Validation and detection

  • Inventory Linux hosts with Intel SGX enabled or SGX drivers loaded.
  • Compare kernel and SGX driver versions against Intel and distribution advisories.
  • Confirm whether local non-admin users can access SGX functionality.
  • Review availability incidents for unexplained SGX or kernel resource exhaustion.
  • Document systems where SGX is unused but still enabled.
Prepared
Confidence
medium
Sources
3

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

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-400: 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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cve · low confidence lookup

CVE-2021-33135 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
Medium
CVSS
5.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
5.5CVSS 3.1MediumCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H1.83.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.5Medium
CVSS 3.1 vector shape for CVE-2021-33135Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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
n/aIntel(R) SGXSee referencesListed
Weakness

CWE details

CWE-400

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

CWE-400 · source CWE mapping

Uncontrolled Resource Consumption

Uncontrolled Resource Consumption represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs