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CVE Record

CVE-2021-3347: An issue was discovered in the Linux kernel through 5.10.11.

An issue was discovered in the Linux kernel through 5.10.11. PI futexes have a kernel stack use-after-free during fault handling, allowing local users to execute code in the kernel, aka CID-34b1a1ce1458.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2021-3347 is a Linux kernel flaw that can let a local user gain kernel-level control. It is not a remote-entry issue by itself, but it matters on shared servers, developer boxes, multi-user systems, and hosts running untrusted workloads.

Executive priority

Patch on a normal high-priority kernel update track, faster for shared or untrusted-workload systems. The business risk is post-compromise privilege escalation: an attacker with local code execution could potentially take full control of the host.

Technical view

The flaw is a CWE-416 use-after-free in PI futex fault handling in Linux kernel versions through 5.10.11. The CVSS 3.1 score is 7.8 with local attack vector, low complexity, low privileges required, no user interaction, and high confidentiality, integrity, and availability impact.

Likely exposure

Linux systems running kernels through 5.10.11, or downstream distribution kernels without the relevant backported fixes, may be exposed. Actual exposure depends on vendor packaging and whether local users or untrusted workloads can execute code on the host.

Exploitation context

The bundle supports local privilege escalation risk via futexes. It does not show CISA KEV listing or active exploitation evidence. Treat exploitation status as unconfirmed from these sources, while still prioritizing due to kernel-level impact.

Researcher notes

Focus validation on PI futex handling and whether downstream kernels include the upstream fix set or vendor backports. The source data names Linux through 5.10.11 but gives incomplete affected-product metadata, so distribution-specific advisory mapping is essential.

Mitigation direction

  • Apply vendor Linux kernel security updates or an upstream kernel containing the referenced fixes.
  • Reboot systems so the patched kernel is actually running.
  • Prioritize shared, multi-user, container-hosting, and internet-facing service hosts first.
  • Check Debian, Fedora, NetApp, and relevant OS vendor guidance for package-specific status.
  • Reduce local access and untrusted workload execution where patching is delayed.

Validation and detection

  • Inventory running Linux kernel versions across servers, endpoints, and cloud images.
  • Map distribution package versions to vendor advisories, not only upstream version numbers.
  • Confirm systems have rebooted into the updated kernel after patch installation.
  • Review vulnerability scanner findings for CVE-2021-3347 and reconcile false positives.
  • Check for unsupported kernels that no longer receive vendor backports.
Prepared
Confidence
high
Sources
10

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-416: 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-2021-3347 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
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
17Source 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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2021-3347Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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-416

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

CWE-416 · source CWE mapping

Use After Free

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

Open CWE intelligenceSame-CWE CVEs