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CVE Record

CVE-2021-47068: net/nfc: fix use-after-free llcp_sock_bind/connect

In the Linux kernel, the following vulnerability has been resolved: net/nfc: fix use-after-free llcp_sock_bind/connect Commits 8a4cd82d ("nfc: fix refcount leak in llcp_sock_connect()") and c33b1cc62 ("nfc: fix refcount leak in llcp_sock_bind()") fixed a refcount leak bug in bind/connect but introduced a use-after-free if the same local is assigned to 2 different sockets. This can be triggered by the following simple program: int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); int sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); memset( &addr, 0, sizeof(struct sockaddr_nfc_llcp) ); addr.sa_family = AF_NFC; addr.nfc_protocol = NFC_PROTO_NFC_DEP; bind( sock1, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) bind( sock2, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) close(sock1); close(sock2); Fix this by assigning NULL to llcp_sock->local after calling nfc_llcp_local_put. This addresses CVE-2021-23134.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel memory safety flaw in NFC LLCP socket handling. A local user could trigger a use-after-free and potentially gain kernel-level impact. It is not a remote internet-facing bug, but it matters on shared Linux systems, endpoints, appliances, or embedded devices with affected kernels and NFC support.

Executive priority

Prioritize remediation on Linux systems with local untrusted users or physical/device feature exposure. It is high severity because successful exploitation can affect confidentiality, integrity, and availability at kernel level, but urgency is lower than remotely exploitable or KEV-listed vulnerabilities.

Technical view

CVE-2021-47068 is a CWE-416 use-after-free in Linux net/nfc LLCP bind/connect paths. Prior refcount-leak fixes introduced unsafe reuse when the same local object is assigned to two sockets. The kernel fix clears llcp_sock->local after nfc_llcp_local_put. CVSS 3.1 is 7.8: local, low complexity, low privilege, no user interaction.

Likely exposure

Exposure is most plausible where affected Linux kernels run with NFC/LLCP support available to local low-privileged users. The source lists affected kernel lines including 4.4.269, 4.9.269, 4.14.233, 4.19.191, 5.4.119, 5.10.37, 5.11.21, 5.12.4, and 5.13.

Exploitation context

The provided CVE record includes a local trigger pattern but KEV is false and no cited source states active exploitation. Treat it as a local privilege-impact kernel vulnerability, not proven in-the-wild exploitation. Public technical detail exists in the kernel fix record, so patch management should not wait for exploit telemetry.

Researcher notes

The record says this addresses CVE-2021-23134, so track duplicate or related advisories carefully. Evidence is strongest for the upstream kernel defect and stable fixes. The source bundle does not establish active exploitation, distro-specific fixed versions, or non-Linux product impact.

Mitigation direction

  • Apply Linux vendor kernel updates containing the stable NFC LLCP fix.
  • Prioritize shared hosts, developer workstations, kiosks, and embedded Linux systems.
  • Check distribution advisories for exact fixed package versions.
  • If NFC is unnecessary, follow vendor guidance for disabling NFC support.
  • Reboot systems after kernel update so the fixed kernel is active.

Validation and detection

  • Inventory running kernel versions across Linux assets.
  • Check whether NFC and LLCP kernel support are present or loadable.
  • Confirm vendor kernel changelogs include the referenced stable commits.
  • Verify systems rebooted into the fixed kernel after update.
  • Document exceptions where affected kernels remain in service.
Prepared
Confidence
high
Sources
11

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-2021-47068 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
3Timeline events
2ADP providers
10Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

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:H1.85.9CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2021-47068Attack 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

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxa1cdd18c49d23ec38097ac2c5b0d761146fc0109, 18013007b596771bf5f5e7feee9586fb0386ad14, 538a6ff11516d38a61e237d2d2dc04c30c845fbe, adbb1d218c5f56dbae052765da83c0f57fce2a31, c89903c9eff219a4695e63715cf922748d743f65, 6fb003e5ae18d8cda4c8a1175d9dd8db12bec049, 8c9e4971e142e2899606a2490b77a1208c1f4638, c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d, c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8dunaffected
LinuxLinux5.12, 0, 4.4.269, 4.9.269, 4.14.233, 4.19.191, 5.4.119, 5.10.37, 5.11.21, 5.12.4, 5.13affected
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.

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