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CVE-2024-47701: ext4: avoid OOB when system.data xattr changes underneath the filesystem

In the Linux kernel, the following vulnerability has been resolved: ext4: avoid OOB when system.data xattr changes underneath the filesystem When looking up for an entry in an inlined directory, if e_value_offs is changed underneath the filesystem by some change in the block device, it will lead to an out-of-bounds access that KASAN detects as an UAF. EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none. loop0: detected capacity change from 2048 to 2047 ================================================================== BUG: KASAN: use-after-free in ext4_search_dir+0xf2/0x1c0 fs/ext4/namei.c:1500 Read of size 1 at addr ffff88803e91130f by task syz-executor269/5103 CPU: 0 UID: 0 PID: 5103 Comm: syz-executor269 Not tainted 6.11.0-rc4-syzkaller #0 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014 Call Trace: <TASK> __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x241/0x360 lib/dump_stack.c:119 print_address_description mm/kasan/report.c:377 [inline] print_report+0x169/0x550 mm/kasan/report.c:488 kasan_report+0x143/0x180 mm/kasan/report.c:601 ext4_search_dir+0xf2/0x1c0 fs/ext4/namei.c:1500 ext4_find_inline_entry+0x4be/0x5e0 fs/ext4/inline.c:1697 __ext4_find_entry+0x2b4/0x1b30 fs/ext4/namei.c:1573 ext4_lookup_entry fs/ext4/namei.c:1727 [inline] ext4_lookup+0x15f/0x750 fs/ext4/namei.c:1795 lookup_one_qstr_excl+0x11f/0x260 fs/namei.c:1633 filename_create+0x297/0x540 fs/namei.c:3980 do_symlinkat+0xf9/0x3a0 fs/namei.c:4587 __do_sys_symlinkat fs/namei.c:4610 [inline] __se_sys_symlinkat fs/namei.c:4607 [inline] __x64_sys_symlinkat+0x95/0xb0 fs/namei.c:4607 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f3e73ced469 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fff4d40c258 EFLAGS: 00000246 ORIG_RAX: 000000000000010a RAX: ffffffffffffffda RBX: 0032656c69662f2e RCX: 00007f3e73ced469 RDX: 0000000020000200 RSI: 00000000ffffff9c RDI: 00000000200001c0 RBP: 0000000000000000 R08: 00007fff4d40c290 R09: 00007fff4d40c290 R10: 0023706f6f6c2f76 R11: 0000000000000246 R12: 00007fff4d40c27c R13: 0000000000000003 R14: 431bde82d7b634db R15: 00007fff4d40c2b0 </TASK> Calling ext4_xattr_ibody_find right after reading the inode with ext4_get_inode_loc will lead to a check of the validity of the xattrs, avoiding this problem.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

An affected Linux kernel can mishandle changing ext4 filesystem metadata and read memory that is no longer valid. The demonstrated result is a kernel use-after-free during a directory operation. This can threaten system stability and, based on the supplied CVSS assessment, confidentiality and integrity. The issue is local rather than remotely reachable by itself.

Executive priority

Address within the normal high-severity kernel patch cycle, accelerating for multi-user systems and environments using loop-backed ext4 storage. The evidence does not support an internet-wide emergency because exploitation is local and active attacks are not reported. Delay only where the vendor confirms the running kernel has a backported fix or is unaffected.

Technical view

CVE-2024-47701 is an ext4 bounds-validation flaw in inline-directory lookup. If the system.data extended attribute’s e_value_offs changes after the inode location is read, ext4_search_dir can access memory out of bounds; KASAN reported a use-after-free. The fix validates the extended attributes immediately after locating the inode and before using them.

Likely exposure

Exposure requires Linux running an affected kernel and using ext4, particularly inline directories on storage whose metadata can change underneath the mounted filesystem. The CVSS vector indicates local, low-privilege access without user interaction, but the evidence does not establish whether low-privilege access alone enables the required storage change. The supplied version data is insufficient for reliable distribution-build mapping.

Exploitation context

The supplied evidence does not support active exploitation, and the bundle marks the CVE as absent from KEV. The failure was demonstrated through syzkaller and KASAN using a QEMU loop device. This proves a kernel memory-safety defect but does not demonstrate reliable real-world compromise.

Researcher notes

The crash occurred on Linux 6.11.0-rc4 during symlink creation after a loop-device capacity change. The source attributes the flaw to e_value_offs changing underneath the filesystem. Stable-branch fixes are linked, but the flattened affected-version list is difficult to interpret. Prefer vendor package mapping over version-string assumptions.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable upstream stable fix.
  • Use distribution or appliance advisories to identify exact fixed packages; the supplied version mapping is ambiguous.
  • Prioritize ext4 systems accessible to untrusted local users or using mutable loop-backed storage.
  • If updates are delayed, seek vendor-approved temporary mitigations; none are named in the supplied sources.

Validation and detection

  • Inventory running kernel builds and ext4 mounts across potentially affected systems.
  • Map each vendor kernel package to CVE-2024-47701 or an applicable stable fix commit.
  • After updating and rebooting, confirm the running kernel is vendor-designated as fixed.
  • Review kernel logs for ext4_search_dir, ext4_find_inline_entry, use-after-free reports, or related crashes.
  • Confirm remediation records cover affected servers, virtual-machine hosts, and Linux-based appliances.
Prepared
Confidence
medium
Sources
11

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-2024-47701 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
3ADP providers
15Source 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-2024-47701Attack 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
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxe8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236, e8e948e7802a2ab05c146d3e72a39b93b5718236unaffected
LinuxLinux3.8, 0, 4.19.323, 5.4.285, 5.10.227, 5.15.168, 6.1.113, 6.6.54, 6.10.13, 6.11.2, 6.12affected
Weakness

CWE details

No CWE listed

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