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CVE Record

CVE-2024-49883: ext4: aovid use-after-free in ext4_ext_insert_extent()

In the Linux kernel, the following vulnerability has been resolved: ext4: aovid use-after-free in ext4_ext_insert_extent() As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is reallocated in ext4_ext_create_new_leaf(), we'll use the stale path and cause UAF. Below is a sample trace with dummy values: ext4_ext_insert_extent path = *ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = *ppath = 2000 if (depth > path[0].p_maxdepth) kfree(path = 2000); *ppath = path = NULL; path = kcalloc() = 3000 *ppath = 3000; return path; /* here path is still 2000, UAF! */ eh = path[depth].p_hdr ================================================================== BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330 Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866 Call Trace: <TASK> ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...] Allocated by task 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] Freed by task 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] ================================================================== So use *ppath to update the path to avoid the above problem.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux ext4 filesystem flaw can make the kernel access memory after freeing it during file allocation. A low-privileged local user may be able to trigger system compromise or disruption. The supplied CVSS score is 7.8. Sanitizer evidence confirms the memory error, but the sources provide no evidence of real-world exploitation.

Executive priority

Treat as a high-priority kernel maintenance issue on multi-user systems, shared compute hosts, and other machines permitting untrusted local execution. Schedule vendor-confirmed kernel updates and required reboots promptly. Internet exposure alone does not establish direct reachability because the supplied attack vector is local.

Technical view

When ext4_ext_create_new_leaf reallocates the extent path through ext4_find_extent, ext4_ext_insert_extent can retain and dereference the freed path. The supplied KASAN trace shows a slab use-after-free during writeback. The correction refreshes the local path from *ppath after reallocation. Linux stable fixes are referenced for multiple kernel branches.

Likely exposure

Systems running affected Linux kernels with writable ext4 filesystems are candidates. Exposure is lower where untrusted users cannot execute locally because the supplied vector is local and requires low privileges. The version data does not reliably map every distribution kernel or vendor backport; verify the running package against vendor advisories and fix history.

Exploitation context

CISA KEV status is false, and the bundle cites no exploitation in the wild or public exploit. Demonstrated evidence is a KASAN failure trace. Practical impact beyond denial of service is not established by the supplied sources, although the CVSS assessment assigns high confidentiality, integrity, and availability impacts.

Researcher notes

The root cause is stale pointer use after *ppath is replaced during extent-tree path reallocation. The trace establishes an invalid eight-byte read in ext4_ext_insert_extent. The bundle does not establish reliable exploitation, affected distribution package ranges, or whether confidentiality and integrity impact is practically achievable.

Mitigation direction

  • Upgrade to a vendor-supported kernel confirmed to fix CVE-2024-49883.
  • For custom kernels, apply the appropriate referenced stable commit through the normal release process.
  • Reboot into the corrected kernel; installing a package alone does not replace the running kernel.
  • Until corrected, reduce untrusted local access to systems using writable ext4 filesystems.

Validation and detection

  • Record the running kernel and distribution package release, not only installed package versions.
  • Confirm vendor guidance or source history maps the running kernel to a referenced fix.
  • Inventory mounted ext4 filesystems and identify untrusted local principals able to initiate writes.
  • After remediation, verify the corrected kernel is running and test normal ext4 write workloads.
  • Review kernel logs for related use-after-free reports; absence of errors does not prove safety.
Prepared
Confidence
medium
Sources
7

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-2024-49883 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
12Source 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-2024-49883Attack 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
LinuxLinux10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279, 10809df84a4d868db61af621bae3658494165279unaffected
LinuxLinux3.18, 0, 4.19.323, 5.4.285, 5.10.227, 5.15.168, 6.1.113, 6.6.55, 6.10.14, 6.11.3, 6.12affected
Weakness

CWE details

No CWE listed

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