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CVE Record

CVE-2024-35854: mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash

In the Linux kernel, the following vulnerability has been resolved: mlxsw: spectrum_acl_tcam: Fix possible use-after-free during rehash The rehash delayed work migrates filters from one region to another according to the number of available credits. The migrated from region is destroyed at the end of the work if the number of credits is non-negative as the assumption is that this is indicative of migration being complete. This assumption is incorrect as a non-negative number of credits can also be the result of a failed migration. The destruction of a region that still has filters referencing it can result in a use-after-free [1]. Fix by not destroying the region if migration failed. [1] BUG: KASAN: slab-use-after-free in mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230 Read of size 8 at addr ffff8881735319e8 by task kworker/0:31/3858 CPU: 0 PID: 3858 Comm: kworker/0:31 Tainted: G W 6.9.0-rc2-custom-00782-gf2275c2157d8 #5 Hardware name: Mellanox Technologies Ltd. MSN3700/VMOD0005, BIOS 5.11 01/06/2019 Workqueue: mlxsw_core mlxsw_sp_acl_tcam_vregion_rehash_work Call Trace: <TASK> dump_stack_lvl+0xc6/0x120 print_report+0xce/0x670 kasan_report+0xd7/0x110 mlxsw_sp_acl_ctcam_region_entry_remove+0x21d/0x230 mlxsw_sp_acl_ctcam_entry_del+0x2e/0x70 mlxsw_sp_acl_atcam_entry_del+0x81/0x210 mlxsw_sp_acl_tcam_vchunk_migrate_all+0x3cd/0xb50 mlxsw_sp_acl_tcam_vregion_rehash_work+0x157/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30 </TASK> Allocated by task 174: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 __kasan_kmalloc+0x8f/0xa0 __kmalloc+0x19c/0x360 mlxsw_sp_acl_tcam_region_create+0xdf/0x9c0 mlxsw_sp_acl_tcam_vregion_rehash_work+0x954/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30 Freed by task 7: kasan_save_stack+0x33/0x60 kasan_save_track+0x14/0x30 kasan_save_free_info+0x3b/0x60 poison_slab_object+0x102/0x170 __kasan_slab_free+0x14/0x30 kfree+0xc1/0x290 mlxsw_sp_acl_tcam_region_destroy+0x272/0x310 mlxsw_sp_acl_tcam_vregion_rehash_work+0x731/0x1300 process_one_work+0x8eb/0x19b0 worker_thread+0x6c9/0xf70 kthread+0x2c9/0x3b0 ret_from_fork+0x4d/0x80 ret_from_fork_asm+0x1a/0x30

HighCVSS 8.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux kernel flaw can free network access-control data while it is still in use during an unsuccessful filter migration. On systems using the mlxsw Spectrum switching driver and affected ACL functionality, this may cause crashes or potentially compromise confidentiality, integrity, and availability. The supplied evidence does not show active exploitation.

Executive priority

Treat this as a high-priority infrastructure update where mlxsw Spectrum ACL functionality is present. Prioritize network switches, appliances, and hosts whose failure would disrupt segmentation or traffic enforcement. Broader emergency action is not supported by the supplied evidence because active exploitation is unconfirmed and reachability depends on a specialized kernel driver path.

Technical view

During mlxsw Spectrum ACL TCAM rehash work, non-negative migration credits were incorrectly treated as proof of completion. If migration failed, the old region could still be destroyed while filters referenced it, causing a slab use-after-free. The fix prevents region destruction after failed migration. KASAN observed the fault in a custom 6.9-rc2 kernel.

Likely exposure

Exposure appears limited to affected Linux kernels operating relevant mlxsw Spectrum ACL TCAM functionality, typically associated with Mellanox Spectrum switching hardware. Systems not using this driver path are unlikely to reach the vulnerable logic. The supplied affected-version data is ambiguous, so confirm exposure against distribution or kernel-vendor advisories and the referenced stable commits.

Exploitation context

The supplied CVSS 3.1 score is 8.8, with low complexity and privileges required. However, the record is not in KEV, and the supplied sources provide no evidence of active exploitation or a public weaponized exploit. The demonstrated outcome is a KASAN-detected kernel use-after-free during rehash processing; real-world exploitability is not established here.

Researcher notes

CWE-416 applies. The failure occurs when a migration error leaves credits non-negative, allowing premature destruction of the source region. Remaining filters then dereference freed region memory during entry removal. The trace identifies mlxsw_sp_acl_ctcam_region_entry_remove and the mlxsw_core rehash workqueue. The bundle does not establish attacker-controlled triggering conditions or reliable security impact beyond the use-after-free.

Mitigation direction

  • Update to a vendor-supported kernel release containing the applicable referenced stable fix.
  • Check Linux distribution and appliance-vendor advisories for corrected package versions.
  • Prioritize updates on systems using mlxsw Spectrum hardware and ACL offload functionality.
  • Follow vendor guidance if an immediate corrected kernel is unavailable.

Validation and detection

  • Inventory kernel versions on systems using Mellanox Spectrum switching hardware.
  • Confirm whether the mlxsw Spectrum driver and ACL offload functionality are active.
  • Map installed kernel packages to the referenced stable fixes or vendor changelogs.
  • Review kernel diagnostics for mlxsw ACL rehash failures, KASAN reports, or unexplained crashes.
  • After updating, verify the running kernel includes the vendor's correction.
Prepared
Confidence
high
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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ATT&CK lookup starting points

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cwe · low confidence lookup

CWE-416: Exact CWE lookup

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cve · low confidence lookup

CVE-2024-35854 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/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.

2CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

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

CVSS vector scores

2 official scores

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
8.8CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H2.85.9CISA-ADP
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

8.8High
CVSS 3.1 vector shape for CVE-2024-35854Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/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
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxc9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430, c9c9af91f1d9a636aecc55302c792538e549a430unaffected
LinuxLinux5.1, 0, 5.4.275, 5.10.216, 5.15.158, 6.1.90, 6.6.30, 6.8.9, 6.9affected
Weakness

CWE details

CWE-416

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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