{"id":"CVE-2026-74371","title":"bpf: fix BPF_PROG_QUERY OOB write and cgroup backward compat","summary":"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 …","severity":"high","cvss":7.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cvssSource":"cna","vendor":"Linux","product":"Linux","affected":["Linux >= 195814a38a6a712bcb44d3dfa5109e926e92bec4 < b78eb6efbf052d44a3a14726aa7c7d5aa2e544d7","Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < a7131340d0f95df9a541257dccab5d85e6bcdd2b","Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < d3d630e8a7f3421bc2d204b87bdff35b4432a8e3","Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < 21c4b99b27f3f85b89256e81b3e997dec0a460d0","Linux 6.17"],"published":"2026-08-15","updated":"2026-09-14","sourceUpdated":"2026-09-14T11:58:45.047Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-74371","references":[{"url":"https://git.kernel.org/stable/c/b78eb6efbf052d44a3a14726aa7c7d5aa2e544d7"},{"url":"https://git.kernel.org/stable/c/a7131340d0f95df9a541257dccab5d85e6bcdd2b"},{"url":"https://git.kernel.org/stable/c/d3d630e8a7f3421bc2d204b87bdff35b4432a8e3"},{"url":"https://git.kernel.org/stable/c/21c4b99b27f3f85b89256e81b3e997dec0a460d0"}],"tags":["cve.org"],"epss":0.00129,"epssPercentile":0.02871,"ingestedAt":"2026-09-14T15:23:07.456Z","slug":"CVE-2026-74371","body":"## Overview\n\nIn 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 -> BPF_TCX_INGRESS/EGRESS\n- netkit_prog_query -> 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.\n\n## Affected\n\n- `Linux >= 195814a38a6a712bcb44d3dfa5109e926e92bec4 < b78eb6efbf052d44a3a14726aa7c7d5aa2e544d7`\n- `Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < a7131340d0f95df9a541257dccab5d85e6bcdd2b`\n- `Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < d3d630e8a7f3421bc2d204b87bdff35b4432a8e3`\n- `Linux >= 1209339844601ec1766f4ff430673fbcfe42bb51 < 21c4b99b27f3f85b89256e81b3e997dec0a460d0`\n- `Linux 6.17`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"twilight","depthScore":43,"depthScoreParts":{"impact":42.9,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}