CVE-2025-39985 (GCVE-0-2025-39985)
Vulnerability from cvelistv5
Published
2025-10-15 07:56
Modified
2025-10-15 07:56
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In the Linux kernel, the following vulnerability has been resolved:
can: mcba_usb: 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 mcba_usb 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, mcba_usb_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 these lines:
usb_msg.dlc = cf->len;
memcpy(usb_msg.data, cf->data, usb_msg.dlc);
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. By
fixing the root cause, this prevents the buffer overflow.
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| ▼ | Linux | Linux |
Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 Version: 51f3baad7de943780ce0c17bd7975df567dd6e14 |
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|
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{
"containers": {
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"drivers/net/can/usb/mcba_usb.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
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"status": "affected",
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"versionType": "git"
},
{
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}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"drivers/net/can/usb/mcba_usb.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.12"
},
{
"lessThan": "4.12",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.4.*",
"status": "unaffected",
"version": "5.4.300",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.245",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.194",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.155",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.109",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.50",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.16.*",
"status": "unaffected",
"version": "6.16.10",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "6.17",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.4.300",
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"vulnerable": true
},
{
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},
{
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{
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"vulnerable": true
},
{
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},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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},
{
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},
{
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}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncan: mcba_usb: 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 mcba_usb 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, mcba_usb_start_xmit() receives a CAN XL frame which it is not\nable to correctly handle and will thus misinterpret it as a CAN frame.\n\nThis can result in a buffer overflow. The driver will consume cf-\u003elen\nas-is with no further checks on these lines:\n\n\tusb_msg.dlc = cf-\u003elen;\n\n\tmemcpy(usb_msg.data, cf-\u003edata, usb_msg.dlc);\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. By\nfixing the root cause, this prevents the buffer overflow."
}
],
"providerMetadata": {
"dateUpdated": "2025-10-15T07:56:04.439Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/0fa9303c4b9493727e0d3a6ac3729300e3013930"
},
{
"url": "https://git.kernel.org/stable/c/37aed407496bf6de8910e588edb04d2435fa7011"
},
{
"url": "https://git.kernel.org/stable/c/6eec67bfb25637f9b51e584cf59ddace59925bc8"
},
{
"url": "https://git.kernel.org/stable/c/ca4e51359608e1f29bf1f2c33c3ddf775b6b7ed1"
},
{
"url": "https://git.kernel.org/stable/c/3664ae91b26d1fd7e4cee9cde17301361f4c89d5"
},
{
"url": "https://git.kernel.org/stable/c/6b9fb82df8868dbe9ffea5874b8d35f951faedbb"
},
{
"url": "https://git.kernel.org/stable/c/b638c3fb0f163e69785ceddb3b434a9437878bec"
},
{
"url": "https://git.kernel.org/stable/c/17c8d794527f01def0d1c8b7dc2d7b8d34fed0e6"
}
],
"title": "can: mcba_usb: populate ndo_change_mtu() to prevent buffer overflow",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2025-39985",
"datePublished": "2025-10-15T07:56:04.439Z",
"dateReserved": "2025-04-16T07:20:57.150Z",
"dateUpdated": "2025-10-15T07:56:04.439Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.1",
"vulnerability-lookup:meta": {
"nvd": "{\"cve\":{\"id\":\"CVE-2025-39985\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-10-15T08:15:36.523\",\"lastModified\":\"2025-10-16T15:29:11.563\",\"vulnStatus\":\"Awaiting Analysis\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\ncan: mcba_usb: 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 mcba_usb 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, mcba_usb_start_xmit() receives a CAN XL frame which it is not\\nable to correctly handle and will thus misinterpret it as a CAN frame.\\n\\nThis can result in a buffer overflow. The driver will consume cf-\u003elen\\nas-is with no further checks on these lines:\\n\\n\\tusb_msg.dlc = cf-\u003elen;\\n\\n\\tmemcpy(usb_msg.data, cf-\u003edata, usb_msg.dlc);\\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. By\\nfixing the root cause, this prevents the buffer overflow.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0fa9303c4b9493727e0d3a6ac3729300e3013930\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/17c8d794527f01def0d1c8b7dc2d7b8d34fed0e6\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/3664ae91b26d1fd7e4cee9cde17301361f4c89d5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/37aed407496bf6de8910e588edb04d2435fa7011\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6b9fb82df8868dbe9ffea5874b8d35f951faedbb\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/6eec67bfb25637f9b51e584cf59ddace59925bc8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/b638c3fb0f163e69785ceddb3b434a9437878bec\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/ca4e51359608e1f29bf1f2c33c3ddf775b6b7ed1\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
}
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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