cbcvebase.
CVE-2025-39986
published 2025-10-15

CVE-2025-39986: In the Linux kernel, the following vulnerability has been resolved: can: sun4i_can: populate ndo_change_mtu() to prevent buffer overflow Sending an PF_PACKET…

PriorityP345high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.16%
5.8th percentile
In the Linux kernel, the following vulnerability has been resolved: can: sun4i_can: populate ndo_change_mtu() to prevent buffer overflow Sending an PF_PACKET allows to bypass the CAN framework logic and to directly reach the xmit() function of a CAN driver. The only check which is performed by the PF_PACKET framework is to make sure that skb->len fits the interface's MTU. Unfortunately, because the sun4i_can driver does not populate its net_device_ops->ndo_change_mtu(), it is possible for an attacker to configure an invalid MTU by doing, for example: $ ip link set can0 mtu 9999 After doing so, the attacker could open a PF_PACKET socket using the ETH_P_CANXL protocol: socket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL)) to inject a malicious CAN XL frames. For example: struct canxl_frame frame = { .flags = 0xff, .len = 2048, }; The CAN drivers' xmit() function are calling can_dev_dropped_skb() to check that the skb is valid, unfortunately under above conditions, the malicious packet is able to go through can_dev_dropped_skb() checks: 1. the skb->protocol is set to ETH_P_CANXL which is valid (the function does not check the actual device capabilities). 2. the length is a valid CAN XL length. And so, sun4ican_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN frame. This can result in a buffer overflow. The driver will consume cf->len as-is with no further checks on this line: dlc = cf->len; Here, cf->len corresponds to the flags field of the CAN XL frame. In our previous example, we set canxl_frame->flags to 0xff. Because the maximum expected length is 8, a buffer overflow of 247 bytes occurs a couple line below when doing: for (i = 0; i data[i], priv->base + (dreg + i * 4)); Populate net_device_ops->ndo_change_mtu() to ensure that the interface's MTU can not be set to anything bigger than CAN_MTU. By fixing the root cause, this prevents the buffer overflow.

Affected

29 ranges· showing 25
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.158-1 (bookworm)linux 6.1.158-1 (bookworm)
debianlinux-6.1< linux 6.1.158-1 (bookworm)linux 6.1.158-1 (bookworm)
linuxlinux
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 063539db42203b29d5aa2adf0cae3d68c646a6b6063539db42203b29d5aa2adf0cae3d68c646a6b6
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 4f382cc887adca8478b9d3e6b81aa6698a95fff44f382cc887adca8478b9d3e6b81aa6698a95fff4
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 60463a1c138900494cb3adae41142a11cd8feb3c60463a1c138900494cb3adae41142a11cd8feb3c
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < a61ff7ac93270d20ca426c027d6d01c8ac8e904ca61ff7ac93270d20ca426c027d6d01c8ac8e904c
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 2e423e1990f3972cbea779883fef52c2f2acb8582e423e1990f3972cbea779883fef52c2f2acb858
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < de77841652e57afbc46e9e1dbf51ee364fc008e1de77841652e57afbc46e9e1dbf51ee364fc008e1
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 7f7b21026a6febdb749f6f6f950427245aa86cce7f7b21026a6febdb749f6f6f950427245aa86cce
linuxlinux>= 0738eff14d817a02ab082c392c96a1613006f158 < 61da0bd4102c459823fbe6b8b43b01fb6ace4a2261da0bd4102c459823fbe6b8b43b01fb6ace4a22
linuxlinux_kernel>= 0 < 5.10.247-15.10.247-1
linuxlinux_kernel>= 0 < 6.1.158-16.1.158-1
linuxlinux_kernel>= 0 < 6.12.57-16.12.57-1
linuxlinux_kernel>= 0 < 6.16.10-16.16.10-1
linuxlinux_kernel>= 0 < 5.15.0-170.1805.15.0-170.180
linuxlinux_kernel>= 0 < 6.8.0-106.1066.8.0-106.106
linuxlinux_kernel>= 4.4.0 < 5.4.3005.4.300
linuxlinux_kernel>= 5.11.0 < 5.15.1945.15.194
linuxlinux_kernel>= 5.16.0 < 6.1.1556.1.155
linuxlinux_kernel>= 5.5.0 < 5.10.2455.10.245
linuxlinux_kernel>= 6.13.0 < 6.16.106.16.10
linuxlinux_kernel>= 6.2.0 < 6.6.1096.6.109
linuxlinux_kernel>= 6.7.0 < 6.12.506.12.50
msrcazl3_kernel_6.6.96.2-2_on_azure_linux_3.0

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.8HIGH
vendor_msrc9.8CRITICAL
vendor_ubuntu7.8HIGH
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.