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CVE Record

CVE-2026-43464: net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ

In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: RX, Fix XDP multi-buf frag counting for legacy RQ XDP multi-buf programs can modify the layout of the XDP buffer when the program calls bpf_xdp_pull_data() or bpf_xdp_adjust_tail(). The referenced commit in the fixes tag corrected the assumption in the mlx5 driver that the XDP buffer layout doesn't change during a program execution. However, this fix introduced another issue: the dropped fragments still need to be counted on the driver side to avoid page fragment reference counting issues. Such issue can be observed with the test_xdp_native_adjst_tail_shrnk_data selftest when using a payload of 3600 and shrinking by 256 bytes (an upcoming selftest patch): the last fragment gets released by the XDP code but doesn't get tracked by the driver. This results in a negative pp_ref_count during page release and the following splat: WARNING: include/net/page_pool/helpers.h:297 at mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core], CPU#12: ip/3137 Modules linked in: [...] CPU: 12 UID: 0 PID: 3137 Comm: ip Not tainted 6.19.0-rc3+ #12 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5e_page_release_fragmented.isra.0+0x4a/0x50 [mlx5_core] [...] Call Trace: <TASK> mlx5e_dealloc_rx_wqe+0xcb/0x1a0 [mlx5_core] mlx5e_free_rx_descs+0x7f/0x110 [mlx5_core] mlx5e_close_rq+0x50/0x60 [mlx5_core] mlx5e_close_queues+0x36/0x2c0 [mlx5_core] mlx5e_close_channel+0x1c/0x50 [mlx5_core] mlx5e_close_channels+0x45/0x80 [mlx5_core] mlx5e_safe_switch_params+0x1a5/0x230 [mlx5_core] mlx5e_change_mtu+0xf3/0x2f0 [mlx5_core] netif_set_mtu_ext+0xf1/0x230 do_setlink.isra.0+0x219/0x1180 rtnl_newlink+0x79f/0xb60 rtnetlink_rcv_msg+0x213/0x3a0 netlink_rcv_skb+0x48/0xf0 netlink_unicast+0x24a/0x350 netlink_sendmsg+0x1ee/0x410 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x232/0x280 ___sys_sendmsg+0x78/0xb0 __sys_sendmsg+0x5f/0xb0 [...] do_syscall_64+0x57/0xc50 This patch fixes the issue by doing page frag counting on all the original XDP buffer fragments for all relevant XDP actions (XDP_TX , XDP_REDIRECT and XDP_PASS). This is basically reverting to the original counting before the commit in the fixes tag. As frag_page is still pointing to the original tail, the nr_frags parameter to xdp_update_skb_frags_info() needs to be calculated in a different way to reflect the new nr_frags.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux mlx5 network-driver bug can mishandle memory references when certain multi-buffer XDP programs reshape received packets. The resulting reference-count corruption may trigger kernel warnings and disrupt availability. Exposure appears limited to systems using the affected mlx5e receive path and relevant XDP behavior.

Executive priority

Treat this as a high-priority availability issue for network infrastructure matching the mlx5e/XDP conditions. Patch confirmed-exposed systems promptly, but avoid assuming fleet-wide exposure until configuration and kernel-branch validation is complete.

Technical view

On the mlx5e legacy receive queue, XDP buffer changes made through bpf_xdp_pull_data() or bpf_xdp_adjust_tail() can leave released fragments untracked. This may produce a negative page-pool reference count during page release. The kernel fix restores counting across original fragments for XDP_TX, XDP_REDIRECT, and XDP_PASS and recalculates nr_frags.

Likely exposure

Prioritize Linux hosts using mlx5e legacy receive queues with multi-buffer XDP programs, especially programs adjusting packet data or tail length. The supplied record lists affected kernel versions but does not establish which distributions, appliances, or default configurations enable the vulnerable path.

Exploitation context

The supplied CVSS is 7.5 and availability-only, with a network, low-complexity, unauthenticated vector. However, the described reproduction depends on a specific mlx5e and XDP configuration. KEV is false, and the supplied sources provide no evidence of active exploitation or a public weaponized exploit.

Researcher notes

The reported regression followed an earlier layout-handling correction. The demonstrated case uses test_xdp_native_adjst_tail_shrnk_data with a 3600-byte payload and 256-byte shrink. No confidentiality or integrity impact is asserted. The supplied version data is unusual, so branch-specific applicability should be verified against the referenced commits and vendor advisories.

Mitigation direction

  • Apply a vendor-supported kernel update containing the applicable referenced stable fix.
  • Confirm the update applies to the deployed kernel branch and distribution build.
  • If no update exists, request supported interim guidance from the kernel or distribution vendor.
  • Prioritize exposed systems running mlx5e with multi-buffer XDP on legacy receive queues.

Validation and detection

  • Inventory kernel versions and identify systems loading mlx5_core or using mlx5e interfaces.
  • Determine whether legacy receive queues and multi-buffer XDP programs are active.
  • Confirm the installed kernel incorporates the applicable referenced fixing commit.
  • Review kernel logs for page-pool warnings or negative pp_ref_count symptoms.
  • Use the named XDP self-test only in an approved, isolated test environment.
Prepared
Confidence
medium
Sources
5

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-2026-43464 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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
0ADP providers
4Source links

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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-43464Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxafd5ba577c10639f62e8120df67dc70ea4b61176, afd5ba577c10639f62e8120df67dc70ea4b61176, afd5ba577c10639f62e8120df67dc70ea4b61176, 72328f25755ee966724f46e3a0e8e59bef2091ba, 0049fd63881505566824e88cfa624638f921c808, d969645b9b7810289bf3c353ea06957373756b8e, 6.6.115, 6.12.56, 6.17.6unaffected
LinuxLinux6.18, 0, 6.18.19, 6.19.9, 7.0affected
Weakness

CWE details

No CWE listed

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