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CVE Record

CVE-2021-47521: can: sja1000: fix use after free in ems_pcmcia_add_card()

In the Linux kernel, the following vulnerability has been resolved: can: sja1000: fix use after free in ems_pcmcia_add_card() If the last channel is not available then "dev" is freed. Fortunately, we can just use "pdev->irq" instead. Also we should check if at least one channel was set up.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel bug in a CAN bus PCMCIA driver. During a specific device setup failure, the driver could reference memory after it was freed. Systems not using this hardware path are unlikely exposed. The source bundle provides no CVSS score and no evidence of active exploitation.

Executive priority

Track as a targeted Linux kernel maintenance issue, not an enterprise-wide emergency from current evidence. Prioritize specialized CAN bus systems and custom kernels; routine server fleets likely have low relevance unless the affected driver is present.

Technical view

The flaw is in can/sja1000 ems_pcmcia_add_card(). If the last channel is unavailable, dev can be freed and then reused; the kernel fix uses pdev->irq and checks that at least one channel was set up. Stable kernel fix commits are referenced, but distro package status is not provided.

Likely exposure

Likely limited to Linux systems using the affected EMS PCMCIA CAN driver path, especially embedded, industrial, automotive, or lab systems with CAN hardware. General Linux servers without this driver or hardware are probably not exposed based on the supplied description.

Exploitation context

The bundle does not cite KEV listing, public exploitation, exploit maturity, required privileges, or impact beyond a kernel use-after-free. Treat exploitation status as unproven, not actively exploited, from the provided evidence.

Researcher notes

Evidence is sparse: no CVSS, CWE, exploit details, or distro-level fixed versions are included. Analysis should focus on driver reachability, hardware presence, kernel branch mapping, and whether downstream vendors backported the stable patch.

Mitigation direction

  • Update to a Linux kernel or vendor package containing the referenced stable fix.
  • Check distro advisories for CVE-2021-47521 package backport status.
  • Disable or remove unused EMS PCMCIA CAN driver support where operationally feasible.
  • Prioritize systems that use CAN bus PCMCIA hardware or custom kernels.

Validation and detection

  • Inventory running kernel versions and compare against vendor advisories for this CVE.
  • Check whether the EMS PCMCIA CAN driver is built, loaded, or required.
  • Review embedded and industrial Linux images separately from standard server fleets.
  • Confirm patched kernels include one of the referenced stable commits or vendor equivalent.
Prepared
Confidence
medium
Sources
7

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.

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CVE-2021-47521 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
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
3Timeline events
2ADP providers
9Source links

SSVC decision data

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

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
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxfd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577e, fd734c6f25aea4b2b44b045e489aec67b388577eunaffected
LinuxLinux3.2, 0, 4.4.295, 4.9.293, 4.14.258, 4.19.221, 5.4.165, 5.10.85, 5.15.8, 5.16affected
Weakness

CWE details

No CWE listed

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