ghsa-5q82-r42m-g49m
Vulnerability from github
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:
-
the skb->protocol is set to ETH_P_CANXL which is valid (the function does not check the actual device capabilities).
-
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.
{
"affected": [],
"aliases": [
"CVE-2025-39988"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-10-15T08:15:36Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: etas_es58x: populate ndo_change_mtu() to prevent buffer overflow\n\nSending an PF_PACKET allows to bypass the CAN framework logic and to\ndirectly reach the xmit() function of a CAN driver. The only check\nwhich is performed by the PF_PACKET framework is to make sure that\nskb-\u003elen fits the interface\u0027s MTU.\n\nUnfortunately, because the etas_es58x driver does not populate its\nnet_device_ops-\u003endo_change_mtu(), it is possible for an attacker to\nconfigure an invalid MTU by doing, for example:\n\n $ ip link set can0 mtu 9999\n\nAfter doing so, the attacker could open a PF_PACKET socket using the\nETH_P_CANXL protocol:\n\n\tsocket(PF_PACKET, SOCK_RAW, htons(ETH_P_CANXL));\n\nto inject a malicious CAN XL frames. For example:\n\n\tstruct canxl_frame frame = {\n\t\t.flags = 0xff,\n\t\t.len = 2048,\n\t};\n\nThe CAN drivers\u0027 xmit() function are calling can_dev_dropped_skb() to\ncheck that the skb is valid, unfortunately under above conditions, the\nmalicious packet is able to go through can_dev_dropped_skb() checks:\n\n 1. the skb-\u003eprotocol is set to ETH_P_CANXL which is valid (the\n function does not check the actual device capabilities).\n\n 2. the length is a valid CAN XL length.\n\nAnd so, es58x_start_xmit() receives a CAN XL frame which it is not\nable to correctly handle and will thus misinterpret it as a CAN(FD)\nframe.\n\nThis can result in a buffer overflow. For example, using the es581.4\nvariant, the frame will be dispatched to es581_4_tx_can_msg(), go\nthrough the last check at the beginning of this function:\n\n\tif (can_is_canfd_skb(skb))\n\t\treturn -EMSGSIZE;\n\nand reach this line:\n\n\tmemcpy(tx_can_msg-\u003edata, cf-\u003edata, cf-\u003elen);\n\nHere, cf-\u003elen corresponds to the flags field of the CAN XL frame. In\nour previous example, we set canxl_frame-\u003eflags to 0xff. Because the\nmaximum expected length is 8, a buffer overflow of 247 bytes occurs!\n\nPopulate net_device_ops-\u003endo_change_mtu() to ensure that the\ninterface\u0027s MTU can not be set to anything bigger than CAN_MTU or\nCANFD_MTU (depending on the device capabilities). By fixing the root\ncause, this prevents the buffer overflow.",
"id": "GHSA-5q82-r42m-g49m",
"modified": "2025-10-15T09:30:17Z",
"published": "2025-10-15T09:30:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39988"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/38c0abad45b190a30d8284a37264d2127a6ec303"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/72de0facc50afdb101fb7197d880407f1abfc77f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/b26cccd87dcddc47b450a40f3b1ac3fe346efcff"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/c4e582e686c4d683c87f2b4a316385b3d81d370f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cbc1de71766f326a44bb798aeae4a7ef4a081cc9"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e587af2c89ecc6382c518febea52fa9ba81e47c0"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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