{"id":"CVE-2026-74371","summary":"bpf: fix BPF_PROG_QUERY OOB write and cgroup backward compat","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: fix BPF_PROG_QUERY OOB write and cgroup backward compat\n\nBPF_PROG_QUERY writes back the 'query.revision' field unconditionally to\nuserspace. If userspace passes a smaller 'bpf_attr' structure (e.g. 40\nbytes, which was the layout before the addition of 'query.revision'),\nthe kernel performs an out-of-bounds write.\n\nFix this by propagating the user-provided attribute size 'uattr_size'\ndown to the cgroup query handlers, and conditionally skipping writing\nthe revision field to userspace when the provided buffer size is\ninsufficient.\n\nquery.revision in bpf_mprog_query is structurally identical to the\ncgroup case: a late tail field, written unconditionally.\n\nBut the backward-compat hazard is not the same.\n\nThe min-historical-size test is per command, and bpf_mprog_query only\nserves attach types that were born with revision in the struct:\n\n- tcx_prog_query -\u003e BPF_TCX_INGRESS/EGRESS\n- netkit_prog_query -\u003e BPF_NETKIT_PRIMARY/PEER\n\ntcx, netkit, the revision field, and bpf_mprog_query itself all landed in\nthe same v6.6 merge window (053c8e1f235d added the mprog query API +\nrevision; tcx in e420bed02507, netkit in 35dfaad7188c). There has never\nbeen a tcx/netkit BPF_PROG_QUERY userspace that doesn't know about\nrevision. So for these commands the minimum legitimate struct already\ncovers offset 56-64 — no old binary can be broken here.\n\nContrast with cgroup: BPF_PROG_QUERY on cgroup attach types shipped in\n2017; revision write-back was bolted on years later (120933984460). That\npath has a real population of pre-revision callers.","modified":"2026-08-16T03:48:49.807863402Z","published":"2026-08-15T05:58:51.610Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74371.json"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/21c4b99b27f3f85b89256e81b3e997dec0a460d0"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a7131340d0f95df9a541257dccab5d85e6bcdd2b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d3d630e8a7f3421bc2d204b87bdff35b4432a8e3"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74371.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74371"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1209339844601ec1766f4ff430673fbcfe42bb51"},{"fixed":"a7131340d0f95df9a541257dccab5d85e6bcdd2b"},{"fixed":"d3d630e8a7f3421bc2d204b87bdff35b4432a8e3"},{"fixed":"21c4b99b27f3f85b89256e81b3e997dec0a460d0"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74371.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"6.17.0"},{"fixed":"6.18.40"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.5"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-74371.json"}}],"schema_version":"1.9.0"}