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CVE Record

CVE-2024-26773: ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found()

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid allocating blocks from corrupted group in ext4_mb_try_best_found() Determine if the group block bitmap is corrupted before using ac_b_ex in ext4_mb_try_best_found() to avoid allocating blocks from a group with a corrupted block bitmap in the following concurrency and making the situation worse. ext4_mb_regular_allocator ext4_lock_group(sb, group) ext4_mb_good_group // check if the group bbitmap is corrupted ext4_mb_complex_scan_group // Scan group gets ac_b_ex but doesn't use it ext4_unlock_group(sb, group) ext4_mark_group_bitmap_corrupted(group) // The block bitmap was corrupted during // the group unlock gap. ext4_mb_try_best_found ext4_lock_group(ac->ac_sb, group) ext4_mb_use_best_found mb_mark_used // Allocating blocks in block bitmap corrupted group

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A race condition in Linux ext4 can allow storage allocation to continue after a block group is marked corrupted, potentially worsening filesystem damage. The supplied CVSS score is 7.8 because successful local abuse could affect confidentiality, integrity, and availability. Exposure depends on the running kernel, ext4 usage, and vendor backports.

Executive priority

Prioritize affected multi-user systems, shared hosting, and important ext4-backed workloads. Treat confirmed vulnerable kernels as a high-priority maintenance update, especially where untrusted local users or workloads exist. This is not evidence of an internet-wide emergency because the supplied vector is local and active exploitation is unconfirmed.

Technical view

During ext4 allocation, a group may pass its bitmap-corruption check, become unlocked, and then be marked corrupted concurrently. ext4_mb_try_best_found() could subsequently allocate from that group using the previously selected extent. The stable-kernel change rechecks corruption while holding the group lock before proceeding.

Likely exposure

Most relevant to systems running an affected Linux kernel with writable ext4 filesystems. The supplied affected list spans 3.12 through several later stable releases, but its version semantics are incomplete. Distribution kernels may contain backported fixes despite older version numbers, so vendor package status must determine exposure.

Exploitation context

The CVSS vector describes local, low-complexity exploitation requiring low privileges and no user interaction. The supplied record is not in KEV, and no cited source states that exploitation is active or that public exploit code exists. The exact attacker-controlled trigger conditions are not established by this bundle.

Researcher notes

The safety issue is a check-to-use concurrency gap around the group lock. Validation should establish whether downstream kernels contain an equivalent fix and whether ext4 allocation reaches the vulnerable path. The bundle does not identify a CWE, reliable proof of concept, or precise exploit preconditions; avoid inferring these from CVSS alone.

Mitigation direction

  • Install the vendor-supported kernel update that incorporates the applicable Linux stable fix.
  • Reboot into the updated kernel so the corrected ext4 code is active.
  • Follow distribution guidance for assessing or repairing suspected ext4 corruption.
  • Maintain verified backups before performing filesystem repair or other storage maintenance.

Validation and detection

  • Inventory running kernel builds and identify systems using writable ext4 filesystems.
  • Check distribution advisories for backport status rather than relying only on upstream version numbers.
  • Confirm the running kernel package includes the applicable stable fix after reboot.
  • Review storage and kernel monitoring for ext4 bitmap-corruption or filesystem-error events.
Prepared
Confidence
medium
Sources
6

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-2024-26773 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

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.

1CVSS vectors
3Timeline events
2ADP providers
11Source links

SSVC decision data

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

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-26773Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
LinuxLinux163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7, 163a203ddb36c36d4a1c942aececda0cc8d06aa7unaffected
LinuxLinux3.12, 0, 4.19.308, 5.4.270, 5.10.211, 5.15.150, 6.1.80, 6.6.19, 6.7.7, 6.8affected
Weakness

CWE details

No CWE listed

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