CVE-2025-39988
Unknown Unknown - Not Provided
BaseFortify

Publication date: 2025-10-15

Last updated on: 2025-10-16

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: can: etas_es58x: 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 etas_es58x 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, es58x_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN(FD) frame. This can result in a buffer overflow. For example, using the es581.4 variant, the frame will be dispatched to es581_4_tx_can_msg(), go through the last check at the beginning of this function: if (can_is_canfd_skb(skb)) return -EMSGSIZE; and reach this line: memcpy(tx_can_msg->data, cf->data, 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! Populate net_device_ops->ndo_change_mtu() to ensure that the interface's MTU can not be set to anything bigger than CAN_MTU or CANFD_MTU (depending on the device capabilities). By fixing the root cause, this prevents the buffer overflow.
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Meta Information
Published
2025-10-15
Last Modified
2025-10-16
Generated
2026-05-07
AI Q&A
2025-10-15
EPSS Evaluated
2026-05-05
NVD
CVE-2025-39988
EUVD
EUVD-2025-34584
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
etas es58x *
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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AI Powered Q&A
Can you explain this vulnerability to me?

This vulnerability exists in the Linux kernel's etas_es58x CAN driver. Because the driver does not implement the ndo_change_mtu() function, an attacker can set an invalid MTU value (e.g., 9999) on a CAN network interface. This allows the attacker to send malicious CAN XL frames via a PF_PACKET socket that bypass normal CAN framework checks. The driver misinterprets these frames as CAN FD frames, leading to a buffer overflow when copying data, potentially causing memory corruption.


How can this vulnerability impact me? :

The vulnerability can lead to a buffer overflow in the CAN driver, which may cause memory corruption, crashes, or potentially allow an attacker to execute arbitrary code or disrupt the normal operation of the affected system. This can compromise system stability and security, especially in environments relying on CAN communication.


How can this vulnerability be detected on my network or system? Can you suggest some commands?

You can detect this vulnerability by checking if any CAN network interface has an invalid MTU set that exceeds the allowed CAN_MTU or CANFD_MTU values. For example, use the command: ip link show can0 to check the MTU of the CAN interface. If the MTU is set to an unusually high value like 9999, it indicates a potential exploitation attempt. Additionally, monitoring for PF_PACKET sockets opened with the ETH_P_CANXL protocol could indicate malicious activity, but no specific commands for this are provided.


What immediate steps should I take to mitigate this vulnerability?

Immediate mitigation involves ensuring that the CAN driver populates the ndo_change_mtu() operation in net_device_ops to prevent setting an invalid MTU larger than CAN_MTU or CANFD_MTU. Until a patch is applied, avoid allowing MTU changes on CAN interfaces to values larger than the maximum allowed. Restrict or monitor the use of PF_PACKET sockets with ETH_P_CANXL protocol to prevent injection of malicious CAN XL frames.


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