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CVE Record

CVE-2021-47616: RDMA: Fix use-after-free in rxe_queue_cleanup

In the Linux kernel, the following vulnerability has been resolved: RDMA: Fix use-after-free in rxe_queue_cleanup On error handling path in rxe_qp_from_init() qp->sq.queue is freed and then rxe_create_qp() will drop last reference to this object. qp clean up function will try to free this queue one time and it causes UAF bug. Fix it by zeroing queue pointer after freeing queue in rxe_qp_from_init().

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2021-47616 is a Linux kernel memory-safety bug in RDMA cleanup code. On a specific error path, the kernel can free the same queue-related object twice, creating a use-after-free condition. The provided sources do not show active exploitation, CVSS scoring, or a remote attack path.

Executive priority

Prioritize through normal kernel patch management unless RDMA/RXE is important in production workloads. Escalate if affected kernels support sensitive multi-tenant, high-availability, or externally exposed infrastructure, because kernel memory bugs can have high impact even when exploit details are unclear.

Technical view

The flaw is in rxe_queue_cleanup handling during rxe_qp_from_init() error processing. qp->sq.queue is freed, then rxe_create_qp() drops the last reference and cleanup can try to free it again. The upstream fix clears the queue pointer after freeing it.

Likely exposure

Exposure likely applies to Linux systems running affected kernel versions with relevant RDMA/RXE code paths reachable. The source bundle lists Linux 5.15 through 5.15.10 and 5.16 as affected, but does not define distribution package status, configurations, or required attacker access.

Exploitation context

The CVE is not listed as KEV, and the supplied sources do not claim active exploitation or provide exploitability details. Treat this as a kernel memory-corruption issue requiring vendor-specific triage rather than evidence of an ongoing campaign.

Researcher notes

Evidence is limited to the CVE record and two Linux stable commits. No CVSS, CWE, exploit status, privilege requirement, or attack vector is provided. Focus validation on affected kernel lineage, commit presence, and whether RDMA/RXE code paths are reachable.

Mitigation direction

  • Apply vendor kernel updates that include the referenced stable fixes.
  • Check Linux distribution advisories for exact package versions and reboot requirements.
  • Confirm the updated, fixed kernel is the one currently booted.
  • Track vendor guidance if RDMA/RXE cannot be promptly patched.

Validation and detection

  • Inventory Linux hosts and identify kernels matching the affected ranges.
  • Check kernel changelogs for CVE-2021-47616 or the referenced stable commits.
  • Confirm whether RDMA/RXE functionality is enabled or operationally required.
  • After patching, verify the running kernel version, not only the installed package.
Prepared
Confidence
medium
Sources
4

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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CVE-2021-47616 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
3Timeline events
2ADP providers
3Source links

SSVC decision data

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

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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux514aee660df493cd673154a6ba6bab745ec47b8c, 514aee660df493cd673154a6ba6bab745ec47b8cunaffected
LinuxLinux5.15, 0, 5.15.10, 5.16affected
Weakness

CWE details

No CWE listed

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