bpf: fix BPF_PROG_QUERY OOB write and cgroup backward compat

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-74371
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-15 06:22:38 UTC
Updated2026-08-17 06:19:31 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: fix BPF_PROG_QUERY OOB write and cgroup backward compat BPF_PROG_QUERY writes back the 'query.revision' field unconditionally to userspace. If userspace passes a smaller 'bpf_attr' structure (e.g. 40 bytes, which was the layout before the addition of 'query.revision'), the kernel performs an out-of-bounds write. Fix this by propagating the user-provided attribute size 'uattr_size' down to the cgroup query handlers, and conditionally skipping writing the revision field to userspace when the provided buffer size is insufficient. query.revision in bpf_mprog_query is structurally identical to the cgroup case: a late tail field, written unconditionally. But the backward-compat hazard is not the same. The min-historical-size test is per command, and bpf_mprog_query only serves attach types that were born with revision in the struct: - tcx_prog_query -> BPF_TCX_INGRESS/EGRESS - netkit_prog_query -> BPF_NETKIT_PRIMARY/PEER tcx, netkit, the revision field, and bpf_mprog_query itself all landed in the same v6.6 merge window (053c8e1f235d added the mprog query API + revision; tcx in e420bed02507, netkit in 35dfaad7188c). There has never been a tcx/netkit BPF_PROG_QUERY userspace that doesn't know about revision. So for these commands the minimum legitimate struct already covers offset 56-64 — no old binary can be broken here. Contrast with cgroup: BPF_PROG_QUERY on cgroup attach types shipped in 2017; revision write-back was bolted on years later (120933984460). That path has a real population of pre-revision callers.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.001270000 probability, percentile 0.027780000 (date 2026-08-17)

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 1209339844601ec1766f4ff430673fbcfe42bb51 a7131340d0f95df9a541257dccab5d85e6bcdd2b git Not specified
CNA Linux Linux affected 1209339844601ec1766f4ff430673fbcfe42bb51 d3d630e8a7f3421bc2d204b87bdff35b4432a8e3 git Not specified
CNA Linux Linux affected 1209339844601ec1766f4ff430673fbcfe42bb51 21c4b99b27f3f85b89256e81b3e997dec0a460d0 git Not specified
CNA Linux Linux affected 6.17 Not specified
CNA Linux Linux unaffected 6.17 semver Not specified
CNA Linux Linux unaffected 6.18.40 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.5 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a7131340d0f95df9a541257dccab5d85e6bcdd2b 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/d3d630e8a7f3421bc2d204b87bdff35b4432a8e3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/21c4b99b27f3f85b89256e81b3e997dec0a460d0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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