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CVE Record

CVE-2024-46857: net/mlx5: Fix bridge mode operations when there are no VFs

In the Linux kernel, the following vulnerability has been resolved: net/mlx5: Fix bridge mode operations when there are no VFs Currently, trying to set the bridge mode attribute when numvfs=0 leads to a crash: bridge link set dev eth2 hwmode vepa [ 168.967392] BUG: kernel NULL pointer dereference, address: 0000000000000030 [...] [ 168.969989] RIP: 0010:mlx5_add_flow_rules+0x1f/0x300 [mlx5_core] [...] [ 168.976037] Call Trace: [ 168.976188] <TASK> [ 168.978620] _mlx5_eswitch_set_vepa_locked+0x113/0x230 [mlx5_core] [ 168.979074] mlx5_eswitch_set_vepa+0x7f/0xa0 [mlx5_core] [ 168.979471] rtnl_bridge_setlink+0xe9/0x1f0 [ 168.979714] rtnetlink_rcv_msg+0x159/0x400 [ 168.980451] netlink_rcv_skb+0x54/0x100 [ 168.980675] netlink_unicast+0x241/0x360 [ 168.980918] netlink_sendmsg+0x1f6/0x430 [ 168.981162] ____sys_sendmsg+0x3bb/0x3f0 [ 168.982155] ___sys_sendmsg+0x88/0xd0 [ 168.985036] __sys_sendmsg+0x59/0xa0 [ 168.985477] do_syscall_64+0x79/0x150 [ 168.987273] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 168.987773] RIP: 0033:0x7f8f7950f917 (esw->fdb_table.legacy.vepa_fdb is null) The bridge mode is only relevant when there are multiple functions per port. Therefore, prevent setting and getting this setting when there are no VFs. Note that after this change, there are no settings to change on the PF interface using `bridge link` when there are no VFs, so the interface no longer appears in the `bridge link` output.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a Linux kernel crash bug in the mlx5 network driver. On systems with Mellanox/NVIDIA mlx5 hardware, changing bridge mode when no virtual functions exist can trigger a null pointer dereference. The main business risk is local denial of service on affected hosts, not confirmed remote compromise.

Executive priority

Treat as routine-to-priority patching for affected infrastructure. Escalate if mlx5-equipped virtualization, cloud, or network hosts rely on automation that modifies bridge settings, because an accidental crash could affect service availability.

Technical view

The mlx5 eswitch bridge-mode path can reference esw->fdb_table.legacy.vepa_fdb when it is null if numvfs is zero. The upstream fix blocks bridge-mode get and set operations when no VFs exist, because the setting is only meaningful with multiple functions per port.

Likely exposure

Exposure appears limited to Linux systems using the mlx5 driver with SR-IOV capable hardware, especially PF interfaces with zero VFs configured. Systems without mlx5 hardware or without bridge-mode management paths are unlikely to be affected based on the provided sources.

Exploitation context

The bundle does not show CISA KEV listing or active exploitation. The described trigger is local administrative network configuration, so practical abuse likely requires local privileges or automation already authorized to change bridge link settings.

Researcher notes

The CVE data lacks CVSS, CWE, and detailed affected package mappings. The strongest evidence is the upstream kernel fix description and stable commit references. Avoid broad claims beyond mlx5 bridge-mode operations with no VFs.

Mitigation direction

  • Apply kernel updates containing the referenced stable mlx5 fixes.
  • Use vendor distribution kernel advisories for exact package versions.
  • Avoid mlx5 bridge-mode changes when numvfs is zero until patched.
  • Review Debian LTS guidance if running affected Debian LTS kernels.

Validation and detection

  • Inventory Linux hosts using mlx5_core or mlx5 hardware.
  • Check whether PF interfaces have numvfs set to zero.
  • Confirm installed kernels include the referenced stable fixes.
  • Review kernel logs for mlx5 NULL pointer dereference crashes.
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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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
2ADP providers
6Source links

SSVC decision data

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

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

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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
LinuxLinux4b89251de024fb85329e4cbd8fbea551ae6c665c, 4b89251de024fb85329e4cbd8fbea551ae6c665c, 4b89251de024fb85329e4cbd8fbea551ae6c665c, 4b89251de024fb85329e4cbd8fbea551ae6c665cunaffected
LinuxLinux5.1, 0, 6.1.111, 6.6.52, 6.10.11, 6.11affected
Weakness

CWE details

No CWE listed

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