{"cve":"CVE-2025-39987","nvd":{"published":"2025-10-15T08:15:36.783","modified":"2026-10-19T21:10:00.160","status":"Deferred","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncan: hi311x: 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->len fits the interface's MTU.\n\nUnfortunately, because the sun4i_can driver does not populate its\nnet_device_ops->ndo_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' 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->protocol 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, hi3110_hard_start_xmit() receives a CAN XL frame which it is\nnot able to correctly handle and will thus misinterpret it as a CAN\nframe. The driver will consume frame->len as-is with no further\nchecks.\n\nThis can result in a buffer overflow later on in hi3110_hw_tx() on\nthis line:\n\n\tmemcpy(buf + HI3110_FIFO_EXT_DATA_OFF,\n\t       frame->data, frame->len);\n\nHere, frame->len corresponds to the flags field of the CAN XL frame.\nIn our previous example, we set canxl_frame->flags to 0xff. Because\nthe maximum expected length is 8, a buffer overflow of 247 bytes\noccurs!\n\nPopulate net_device_ops->ndo_change_mtu() to ensure that the\ninterface's MTU can not be set to anything bigger than CAN_MTU. By\nfixing the root cause, this prevents the buffer overflow.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8},"cwes":[],"references":["https://git.kernel.org/stable/c/57d332ce8c921d0e340650470bb0c1d707f216ee","https://git.kernel.org/stable/c/7ab85762274c0fa997f0ef9a2307b2001aae43c4","https://git.kernel.org/stable/c/8f351db6b2367991f0736b2cff082f5de4872113","https://git.kernel.org/stable/c/ac1c7656fa717f29fac3ea073af63f0b9919ec9a","https://git.kernel.org/stable/c/be1b25005fd0f9d4e78bec6695711ef87ee33398"],"products":[],"source":"nvd","synced_at":"2026-10-21T03:43:09.190223697+00:00"},"epss":{"cve":"CVE-2025-39987","score":0.00176,"percentile":0.07105,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}