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CVE Record

CVE-2023-54021: ext4: set goal start correctly in ext4_mb_normalize_request

In the Linux kernel, the following vulnerability has been resolved: ext4: set goal start correctly in ext4_mb_normalize_request We need to set ac_g_ex to notify the goal start used in ext4_mb_find_by_goal. Set ac_g_ex instead of ac_f_ex in ext4_mb_normalize_request. Besides we should assure goal start is in range [first_data_block, blocks_count) as ext4_mb_initialize_context does. [ Added a check to make sure size is less than ar->pright; otherwise we could end up passing an underflowed value of ar->pright - size to ext4_get_group_no_and_offset(), which will trigger a BUG_ON later on. - TYT ]

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2023-54021 is a Linux kernel ext4 filesystem bug. The public record describes incorrect goal-block handling that can reach a kernel BUG condition. Business urgency depends on whether affected Linux kernels and ext4 filesystems are present; the sources do not provide CVSS, confirmed impact scope, or exploitation evidence.

Executive priority

Treat as a kernel maintenance item until impact is clarified. Prioritize patching internet-facing, multi-user, and business-critical Linux systems using ext4, but avoid emergency escalation without vendor severity or exploitation evidence.

Technical view

The ext4 multiblock allocator used the wrong extent field in ext4_mb_normalize_request and lacked range checks for the allocation goal. The fix sets ac_g_ex correctly and checks bounds to prevent an underflow before ext4_get_group_no_and_offset(), which could later trigger BUG_ON.

Likely exposure

Potentially exposed systems are Linux hosts running affected kernel versions that use ext4. The CVE lists affected Linux versions including 2.6.25 through 6.4-era stable lines, but distro backports require vendor-specific verification.

Exploitation context

CISA KEV status is false in the source bundle. The provided sources do not claim active exploitation, public exploit availability, remote reachability, privilege impact, or a complete attacker model.

Researcher notes

The record is sparse: no CVSS, CWE, exploit status, or affected configuration detail beyond Linux kernel versions and stable commits. Analysis should focus on reproducing the allocator bounds condition safely and mapping distro backports.

Mitigation direction

  • Apply vendor kernel updates that include the referenced Linux stable fixes.
  • Prioritize Linux systems using ext4 on affected kernel branches.
  • Check distribution advisories for backported package names and fixed builds.
  • If no update is available, follow vendor guidance for temporary risk reduction.

Validation and detection

  • Inventory Linux kernel versions across servers, endpoints, and appliances.
  • Confirm whether ext4 filesystems are mounted or used on those systems.
  • Compare installed kernel builds against vendor fixed versions or stable commits.
  • Review kernel logs for ext4-related BUG, oops, or allocation errors.
Prepared
Confidence
medium
Sources
10

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-2023-54021 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
0ADP providers
9Source links

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.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxc9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55a, c9de560ded61faa5b754137b7753da252391c55aunaffected
LinuxLinux2.6.25, 0, 4.14.316, 4.19.284, 5.4.244, 5.10.181, 5.15.113, 6.1.30, 6.3.4, 6.4affected
Weakness

CWE details

No CWE listed

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