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CVE Record

CVE-2021-46023: An Untrusted Pointer Dereference was discovered in function mrb_vm_exec in mruby before 3.1.0-rc.

An Untrusted Pointer Dereference was discovered in function mrb_vm_exec in mruby before 3.1.0-rc. The vulnerability causes a segmentation fault and application crash.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-46023 is a crash vulnerability in mruby before 3.1.0-rc. A vulnerable application can hit a segmentation fault in the mruby VM, causing service interruption. The sourced record rates availability impact as high, with no confidentiality or integrity impact identified.

Executive priority

Treat this as a high-priority availability risk for services that use mruby. It is most urgent where mruby is exposed through public or unauthenticated workflows. Business impact is service disruption rather than confirmed compromise of data.

Technical view

The issue is an untrusted pointer dereference in mrb_vm_exec, mapped to CWE-119. The CVSS 3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H, score 7.5. The source bundle does not provide affected CPEs, exploit detail, or product-specific deployment context.

Likely exposure

Exposure is likely limited to systems embedding or running mruby versions before 3.1.0-rc in reachable application paths. The bundle’s affected-product metadata is n/a, so teams must confirm mruby usage through software inventory, build manifests, and dependency review.

Exploitation context

The CVE record supports network-reachable, low-complexity denial of service characteristics. CISA KEV status is false in the bundle, and no cited source states active exploitation. Public evidence provided here supports crash impact, not data theft or code execution.

Researcher notes

The provided sources are sparse: affected CPEs are absent, and only the mruby issue is referenced. Analysis should avoid assuming exploit maturity or broader product impact. Focus validation on exact mruby version presence and whether untrusted inputs can reach VM execution.

Mitigation direction

  • Identify applications, services, firmware, or tools that embed mruby.
  • Move mruby deployments off versions before 3.1.0-rc following project guidance.
  • Prioritize internet-facing or unauthenticated paths using mruby first.
  • Reduce exposure of mruby-backed services where upgrade timing is constrained.
  • Monitor vendor or upstream mruby advisories for precise fix guidance.

Validation and detection

  • Check dependency manifests and SBOMs for mruby versions before 3.1.0-rc.
  • Confirm whether mruby code paths are reachable over a network.
  • Review crash logs for segmentation faults around mruby VM execution.
  • Verify upgraded builds no longer include vulnerable mruby versions.
  • Document systems where mruby usage cannot be confirmed.
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-119: 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-2021-46023 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2021-46023Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/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/an/an/aListed
Weakness

CWE details

CWE-119

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

CWE-119 · source CWE mapping

Improper Restriction of Operations within the Bounds of a Memory Buffer

Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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