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VulnerabilityPublished Updated

CVE-2025-39987: Linux kernel · can: hi311x: populate ndo_change_mtu() to prevent buffer overflow

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 7.8 High · fixed in 5.15.0-1110.119~20.04.1 : patch Linux kernel soon.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 5.15.0-1110.119~20.04.1, 5.15.0-1100.109~20.04.1, 5.15.0-1100.107~20.04.2 +2
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 15 Oct 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
linux-azureAffected
  • <5.15.0-1100.107~20.04.2
  • <5.15.0-1110.119~20.04.1
  • <5.15.0-1100.109~20.04.1
  • <5.15.0-170.180~20.04.3
  • <5.15.0-1094.97~20.04.1
Fixed in
  • 5.15.0-1100.107~20.04.2
  • 5.15.0-1110.119~20.04.1
  • 5.15.0-1100.109~20.04.1
  • 5.15.0-170.180~20.04.3
  • 5.15.0-1094.97~20.04.1

AI-suggested

A fix is available that populates the net_device_ops->ndo_change_mtu() function in the hi311x CAN driver to prevent setting MTU values larger than CAN_MTU. Applying this fix prevents the buffer overflow by enforcing valid MTU limits. Users should update their Linux kernel to a version that includes this patch. No additional mitigations are indicated.

Description

In the Linux kernel, the following vulnerability has been resolved: can: hi311x: 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, hi3110_hard_start_xmit() receives a CAN XL frame which it is not able to correctly handle and will thus misinterpret it as a CAN frame. The driver will consume frame->len as-is with no further checks. This can result in a buffer overflow later on in hi3110_hw_tx() on this line: memcpy(buf + HI3110_FIFO_EXT_DATA_OFF, frame->data, frame->len); Here, frame->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. By fixing the root cause, this prevents the buffer overflow.

References

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