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CVE Record

CVE-2021-47541: net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources()

In the Linux kernel, the following vulnerability has been resolved: net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources() In mlx4_en_try_alloc_resources(), mlx4_en_copy_priv() is called and tmp->tx_cq will be freed on the error path of mlx4_en_copy_priv(). After that mlx4_en_alloc_resources() is called and there is a dereference of &tmp->tx_cq[t][i] in mlx4_en_alloc_resources(), which could lead to a use after free problem on failure of mlx4_en_copy_priv(). Fix this bug by adding a check of mlx4_en_copy_priv() This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_MLX4_EN=m show no new warnings, and our static analyzer no longer warns about this code.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel use-after-free bug in the mlx4_en Ethernet driver. It was found by static analysis and may be hard to trigger. The main business concern is kernel stability and possible memory-safety exposure on systems using this driver, not a confirmed active attack campaign.

Executive priority

Treat as a targeted Linux maintenance item, not an emergency, unless critical infrastructure uses mlx4_en. Patch during the next appropriate kernel update window after confirming vendor coverage.

Technical view

mlx4_en_try_alloc_resources() called mlx4_en_copy_priv(), whose error path could free tmp->tx_cq. The code then called mlx4_en_alloc_resources(), which dereferenced tmp->tx_cq entries. Stable kernel fixes add a check for mlx4_en_copy_priv() before continuing.

Likely exposure

Exposure is likely limited to Linux systems running affected kernel versions with CONFIG_MLX4_EN enabled or the mlx4_en module loaded, typically systems using Mellanox mlx4 Ethernet hardware. Systems without this driver path are less likely exposed.

Exploitation context

The source bundle does not show KEV listing, public exploitation, CVSS, or a working exploit. The upstream description says the bug was static-analysis-found, cross-reviewed, and may be false positive or hard to trigger.

Researcher notes

Evidence supports a kernel driver memory-safety bug with incomplete exploitability details. Do not assume remote reachability, privilege escalation, or crash impact without additional vendor or upstream analysis.

Mitigation direction

  • Update to a kernel release containing the referenced stable fixes.
  • Prioritize hosts using the mlx4_en driver or Mellanox mlx4 network hardware.
  • If patching is delayed, check vendor distribution advisories for supported mitigations.
  • Avoid inventing compensating controls; follow kernel or Linux vendor guidance.

Validation and detection

  • Inventory kernels and identify systems with mlx4_en enabled or loaded.
  • Compare installed kernel builds against vendor advisories and stable fix inclusion.
  • Review package changelogs for CVE-2021-47541 or the referenced commits.
  • Confirm post-update kernels no longer contain the vulnerable code path.
Prepared
Confidence
medium
Sources
8

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

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CVE-2021-47541 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
7Source 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

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxec25bc04ed8e12947738468cbe2191f1529f9e39, ec25bc04ed8e12947738468cbe2191f1529f9e39, ec25bc04ed8e12947738468cbe2191f1529f9e39, ec25bc04ed8e12947738468cbe2191f1529f9e39, ec25bc04ed8e12947738468cbe2191f1529f9e39, ec25bc04ed8e12947738468cbe2191f1529f9e39unaffected
LinuxLinux4.7, 0, 4.14.257, 4.19.220, 5.4.164, 5.10.84, 5.15.7, 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.