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CVE-2026-64036

33
FAUCET Score

In the Linux kernel, the following vulnerability has been resolved: cgroup/rstat: validate cpu before css_rstat_cpu() access css_rstat_updated() is exposed as a BPF kfunc and accepts a caller-provided cpu argument. The function uses cpu for per-cpu rstat lookups without checking whether it refers to a valid possible CPU. A BPF iter/cgroup program with CAP_BPF and CAP_PERFMON can pass an invalid cpu value. On an unfixed UBSCAN_BOUNDS test kernel, cpu == 0x7fffffff triggers: UBSAN: array-index-out-of-bounds in kernel/cgroup/rstat.c:31:9 index 2147483647 is out of range for type 'long unsigned int [64]' Call Trace: css_rstat_updated bpf_iter_run_prog cgroup_iter_seq_show bpf_seq_read Add cpu validation to the BPF-facing css_rstat_updated() kfunc and move the common implementation to __css_rstat_updated() for in-kernel callers.

First published: Jul 19, 2026Last modified: Jul 20, 2026

Impacted Technologies

VendorProductVersion(s)CPE
LinuxLinux
6.1CNA affecteddefault affected
LinuxLinux
>= a319185be9f5ad13c2a296d448ac52ffe45d194c, < 6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6, >= a319185be9f5ad13c2a296d448ac52ffe45d194c, < 8817005efbdfdf5d4e4814cb5dc52b53d12917d7, >= a319185be9f5ad13c2a296d448ac52ffe45d194c, < fd2bd9fa7700ddf28296486b2598cff2f80cc819CNA affecteddefault unaffected

CVSS Data

CVSS version used by this source: 3.1

7.8HIGH

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
0.13%
Probability of exploitation in next 30 days
EPSS Percentile
2.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0013 is in the 13th percentile among its peer group of 17,070 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.2 Bluesky, 0.1 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (4)

ubuntupatch availablevia ubuntu_usn
Product: linux-ibm (resolute)Fixed in: 7.0.0-1010.10
ubuntupatch availablevia ubuntu_usn
Product: linux-oracle (resolute)Fixed in: 7.0.0-1008.8
ubuntupatch availablevia ubuntu_usn
Product: linux-azure (resolute)Fixed in: 7.0.0-1010.10
ubuntupatch availablevia ubuntu_usn
Product: linux-azure-fde (resolute)Fixed in: 7.0.0-1009.9

Vendor Advisories (3)

ubuntuUSN-8603-1

Linux kernel (Azure) vulnerabilities

Jul 24, 2026
ubuntuUSN-8593-1

Linux kernel vulnerabilities

Jul 23, 2026
microsoft2026-Jul/CVE-2026-64036Moderate

cgroup/rstat: validate cpu before css_rstat_cpu() access

Jul 14, 2026

References

git.kernel.org / stable/c/6a01413a4e8fcb0263d7bef5075c5f8f4eb3a8b6
git.kernel.org / stable/c/8817005efbdfdf5d4e4814cb5dc52b53d12917d7
git.kernel.org / stable/c/fd2bd9fa7700ddf28296486b2598cff2f80cc819