{"cve":"CVE-2025-21921","nvd":{"published":"2025-04-01T16:15:22.790","modified":"2026-06-17T08:44:37.040","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethtool: netlink: Allow NULL nlattrs when getting a phy_device\n\nethnl_req_get_phydev() is used to lookup a phy_device, in the case an\nethtool netlink command targets a specific phydev within a netdev's\ntopology.\n\nIt takes as a parameter a const struct nlattr *header that's used for\nerror handling :\n\n       if (!phydev) {\n               NL_SET_ERR_MSG_ATTR(extack, header,\n                                   \"no phy matching phyindex\");\n               return ERR_PTR(-ENODEV);\n       }\n\nIn the notify path after a ->set operation however, there's no request\nattributes available.\n\nThe typical callsite for the above function looks like:\n\n\tphydev = ethnl_req_get_phydev(req_base, tb[ETHTOOL_A_XXX_HEADER],\n\t\t\t\t      info->extack);\n\nSo, when tb is NULL (such as in the ethnl notify path), we have a nice\ncrash.\n\nIt turns out that there's only the PLCA command that is in that case, as\nthe other phydev-specific commands don't have a notification.\n\nThis commit fixes the crash by passing the cmd index and the nlattr\narray separately, allowing NULL-checking it directly inside the helper.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/1f458fa42c29144cef280e05bc49fc21b873d897","https://git.kernel.org/stable/c/637399bf7e77797811adf340090b561a8f9d1213","https://git.kernel.org/stable/c/639c70352958735addbba5ae7dd65985da96e061"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:00:57.946988208+00:00"},"epss":{"cve":"CVE-2025-21921","score":0.00209,"percentile":0.11133,"date":"2026-10-31"},"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."]}