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CVE Record

CVE-2021-4218: A flaw was found in the Linux kernel’s implementation of reading the SVC RDMA counters.

A flaw was found in the Linux kernel’s implementation of reading the SVC RDMA counters. Reading the counter sysctl panics the system. This flaw allows a local attacker with local access to cause a denial of service while the system reboots. The issue is specific to CentOS/RHEL.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

CVE-2021-4218 can let someone with local access crash a CentOS/RHEL system by triggering a Linux kernel panic while reading SVC RDMA counters. The likely business impact is availability disruption and reboot, not data theft based on the provided sources.

Executive priority

Treat this as a localized availability risk. Prioritize internet-facing or business-critical CentOS/RHEL infrastructure only if untrusted local access exists or unexpected reboots would materially disrupt operations.

Technical view

The flaw is in the Linux kernel implementation for reading SVC RDMA counters. The provided description says reading the counter sysctl can panic the system. It is categorized as CWE-665 and described as specific to CentOS/RHEL, but exact affected versions and fixed packages are not provided in the bundle.

Likely exposure

Exposure appears limited to CentOS/RHEL systems with the affected kernel behavior reachable by a local user. The source bundle does not identify exact versions, packages, or whether all RDMA-related configurations are affected.

Exploitation context

The bundle says exploitation requires local access and causes denial of service through system reboot. There is no KEV listing and no cited source in the bundle claims active exploitation in the wild.

Researcher notes

Evidence is sparse: no CVSS, exact versions, patch identifiers, or exploit evidence are included. The key assertion is local denial of service through kernel panic when reading SVC RDMA counters on CentOS/RHEL.

Mitigation direction

  • Check Red Hat and CentOS guidance for affected and fixed kernel packages.
  • Prioritize vendor-supported kernel updates once applicable fixes are identified.
  • Limit unnecessary local account access on potentially affected systems.
  • Track the Red Hat Bugzilla and advisory for remediation details.
  • Assess business-critical CentOS/RHEL hosts for reboot tolerance and monitoring.

Validation and detection

  • Inventory CentOS/RHEL systems and their installed kernel versions.
  • Review whether SVC RDMA counter sysctls are present on those hosts.
  • Compare kernel packages against Red Hat or CentOS advisory guidance.
  • Check logs for unexplained kernel panics or sudden reboots.
  • Confirm local account exposure on systems running affected kernels.
Prepared
Confidence
medium
Sources
5

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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cwe · low confidence lookup

CWE-665: 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-2021-4218 mapping review

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
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.

0CVSS vectors
0Timeline events
0ADP providers
4Source links

CVSS and timeline data

No CVSS vectors or timeline events were available in the normalized CVE source material.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/akernelNAListed
Weakness

CWE details

CWE-665

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

CWE-665 · source CWE mapping

Improper Initialization

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

Open CWE intelligenceSame-CWE CVEs