In the Linux kernel, the following vulnerability has been resolved: net/mlx5e: RX, Fix XDP multi-buf frag counting for striding 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. The issue was discovered by the drivers/net/xdp.py selftest, more specifically the test_xdp_native_tx_mb: - The mlx5 driver allocates a page_pool page and initializes it with a frag counter of 64 (pp_ref_count=64) and the internal frag counter to 0. - The test sends one packet with no payload. - On RX (mlx5e_skb_from_cqe_mpwrq_nonlinear()), mlx5 configures the XDP buffer with the packet data starting in the first fragment which is the page mentioned above. - The XDP program runs and calls bpf_xdp_pull_data() which moves the header into the linear part of the XDP buffer. As the packet doesn't contain more data, the program drops the tail fragment since it no longer contains any payload (pp_ref_count=63). - mlx5 device skips counting this fragment. Internal frag counter remains 0. - mlx5 releases all 64 fragments of the page but page pp_ref_count is 63 => negative reference counting error. Resulting splat during the test: WARNING: CPU: 0 PID: 188225 at ./include/net/page_pool/helpers.h:297 mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core] Modules linked in: [...] CPU: 0 UID: 0 PID: 188225 Comm: ip Not tainted 6.18.0-rc7_for_upstream_min_debug_2025_12_08_11_44 #1 NONE Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP: 0010:mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core] [...] Call Trace: <TASK> mlx5e_free_rx_mpwqe+0x20a/0x250 [mlx5_core] mlx5e_dealloc_rx_mpwqe+0x37/0xb0 [mlx5_core] mlx5e_free_rx_descs+0x11a/0x170 [mlx5_core] mlx5e_close_rq+0x78/0xa0 [mlx5_core] mlx5e_close_queues+0x46/0x2a0 [mlx5_core] mlx5e_close_channel+0x24/0x90 [mlx5_core] mlx5e_close_channels+0x5d/0xf0 [mlx5_core] mlx5e_safe_switch_params+0x2ec/0x380 [mlx5_core] mlx5e_change_mtu+0x11d/0x490 [mlx5_core] mlx5e_change_nic_mtu+0x19/0x30 [mlx5_core] netif_set_mtu_ext+0xfc/0x240 do_setlink.isra.0+0x226/0x1100 rtnl_newlink+0x7a9/0xba0 rtnetlink_rcv_msg+0x220/0x3c0 netlink_rcv_skb+0x4b/0xf0 netlink_unicast+0x255/0x380 netlink_sendmsg+0x1f3/0x420 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x1e8/0x240 ___sys_sendmsg+0x7c/0xb0 [...] __sys_sendmsg+0x5f/0xb0 do_syscall_64+0x55/0xc70 The problem applies for XDP_PASS as well which is handled in a different code path in the driver. 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.

An update of the linux package has been released.

The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.

  - net/mlx5e: RX, Fix XDP multi-buf frag counting for striding 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.
    The issue was discovered by the drivers/net/xdp.py selftest, more specifically the test_xdp_native_tx_mb:
    - The mlx5 driver allocates a page_pool page and initializes it with a frag counter of 64     (pp_ref_count=64) and the internal frag counter to 0. - The test sends one packet with no payload. - On RX     (mlx5e_skb_from_cqe_mpwrq_nonlinear()), mlx5 configures the XDP buffer with the packet data starting in     the first fragment which is the page mentioned above. - The XDP program runs and calls bpf_xdp_pull_data()     which moves the header into the linear part of the XDP buffer. As the packet doesn't contain more data,     the program drops the tail fragment since it no longer contains any payload (pp_ref_count=63). - mlx5     device skips counting this fragment. Internal frag counter remains 0. - mlx5 releases all 64 fragments of     the page but page pp_ref_count is 63 => negative reference counting error. Resulting splat during the     test: WARNING: CPU: 0 PID: 188225 at ./include/net/page_pool/helpers.h:297     mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core] Modules linked in: [...] CPU: 0 UID: 0 PID:
    188225 Comm: ip Not tainted 6.18.0-rc7_for_upstream_min_debug_2025_12_08_11_44 #1 NONE Hardware name: QEMU     Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 RIP:
    0010:mlx5e_page_release_fragmented.isra.0+0xbd/0xe0 [mlx5_core] [...] Call Trace: <TASK>     mlx5e_free_rx_mpwqe+0x20a/0x250 [mlx5_core] mlx5e_dealloc_rx_mpwqe+0x37/0xb0 [mlx5_core]     mlx5e_free_rx_descs+0x11a/0x170 [mlx5_core] mlx5e_close_rq+0x78/0xa0 [mlx5_core]     mlx5e_close_queues+0x46/0x2a0 [mlx5_core] mlx5e_close_channel+0x24/0x90 [mlx5_core]     mlx5e_close_channels+0x5d/0xf0 [mlx5_core] mlx5e_safe_switch_params+0x2ec/0x380 [mlx5_core]     mlx5e_change_mtu+0x11d/0x490 [mlx5_core] mlx5e_change_nic_mtu+0x19/0x30 [mlx5_core]     netif_set_mtu_ext+0xfc/0x240 do_setlink.isra.0+0x226/0x1100 rtnl_newlink+0x7a9/0xba0     rtnetlink_rcv_msg+0x220/0x3c0 netlink_rcv_skb+0x4b/0xf0 netlink_unicast+0x255/0x380     netlink_sendmsg+0x1f3/0x420 __sock_sendmsg+0x38/0x60 ____sys_sendmsg+0x1e8/0x240 ___sys_sendmsg+0x7c/0xb0     [...] __sys_sendmsg+0x5f/0xb0 do_syscall_64+0x55/0xc70 The problem applies for XDP_PASS as well which is     handled in a different code path in the driver. 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. (CVE-2026-43465)

Note that Nessus relies on the presence of the package as reported by the vendor.

ID	Name	Product	Family	Type	Severity
334126	Photon OS 5.0: Linux PHSA-2026-5.0-92-0931	Nessus	PhotonOS Local Security Checks	Local	critical
331915	Photon OS 5.0: Linux PHSA-2026-5.0-0931	Nessus	PhotonOS Local Security Checks	Local	critical
329305	openSUSE 16: cluster-md-kmp-64kb / cluster-md-kmp-azure / cluster-md-kmp-default / etc (openSUSE-SU-2026:21388-1)	Nessus	SuSE Local Security Checks	Local	high
329149	SUSE SLED15: cluster-md-kmp-default / dlm-kmp-default / gfs2-kmp-default / etc (SUSE-SU-2026:3166-1)	Nessus	SuSE Local Security Checks	Local	medium
313347	Linux Distros Unpatched Vulnerability : CVE-2026-43465	Nessus	Misc.	Local	critical
311340	Amazon Linux 2023 : bpftool6.18, kernel6.18, kernel6.18-devel (ALAS2023-2026-1596)	Nessus	Amazon Linux Local Security Checks	Local	high

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CVE-2026-43465

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