Security readout for executives and security teams
Plain-English summary
This is a Linux kernel RDMA bug where failed queue-pair creation can leave cleanup code using freed memory. It appears most relevant to systems using RDMA/uverbs and mlx5-related drivers. The public record does not provide CVSS, confirmed exploitation, or a complete operational impact statement.
Executive priority
Prioritize RDMA-capable Linux servers, HPC systems, storage fabrics, and virtualization hosts. Treat as a focused kernel hygiene issue unless your environment exposes RDMA interfaces broadly or runs untrusted local workloads.
Technical view
The flaw is a use-after-free in RDMA core during QP creation failure handling. The fix sets send and receive completion-queue pointers before forwarding creation to drivers, because mlx5 cleanup relies on valid CQ pointers during QP destroy after failure.
Likely exposure
Exposure is most likely on Linux 5.15-era kernels with RDMA userspace verbs enabled and relevant RDMA drivers such as mlx5_ib present. General Linux hosts without RDMA hardware, modules, or uverbs access appear less likely to be exposed based on the provided evidence.
Exploitation context
The bundle shows a KASAN use-after-free trace reachable through ib_uverbs ioctl during QP creation, but it does not cite public exploitation or weaponized details. CISA KEV status is false, so active exploitation should not be assumed.
Researcher notes
The evidence centers on cleanup after QP creation failure, where mlx5 destroy handling depends on initialized CQ pointers. The record does not include CVSS, CWE, exploit maturity, or distribution-specific affected package versions, so validation should rely on vendor kernel backports.
Mitigation direction
- Update to a vendor kernel containing the referenced stable RDMA fixes.
- Check Linux distribution advisories for CVE-2021-47196 coverage.
- Restrict access to RDMA userspace verbs devices where not required.
- Disable unused RDMA drivers or hardware support following vendor guidance.
Validation and detection
- Inventory kernels around Linux 5.15 and confirm vendor backport status.
- Check whether RDMA modules such as ib_uverbs and mlx5_ib are loaded.
- Identify hosts exposing RDMA userspace device nodes to local users or workloads.
- Confirm patched kernels include the referenced stable commits or equivalent backports.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
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.
CVE-2021-47196 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Unknown
- CVSS
- Not scored
- Known Exploited
- No
- Published
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.
SSVC decision data
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://git.kernel.org/stable/c/b70e072feffa0ba5c41a99b9524b9878dee7748eCVE reference, Linux
- https://git.kernel.org/stable/c/6cd7397d01c4a3e09757840299e4f114f0aa5fa0CVE reference, Linux
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.