Root code execution via incorrect eBPF bounds
Published May 21, 2021 · Updated Aug 3, 2024
Privilege escalation in Linux Kernel 5.11.15 allows local users to execute arbitrary code in the kernel through a crafted eBPF program. The eBPF verifier's __reg_combine_64_into_32() function derives lower-32-bit unsigned bounds from only one 64-bit bound, accepting a register value that enables out-of-bounds reads and writes. Low-privileged code execution and bpf system-call access are required; successful exploitation enables root access and container escape.
Summary
What happened
Privilege escalation in Linux Kernel 5.11.15 allows local users to execute arbitrary code in the kernel through a crafted eBPF program. The eBPF verifier's __reg_combine_64_into_32() function derives lower-32-bit unsigned bounds from only one 64-bit bound, accepting a register value that enables out-of-bounds reads and writes. Low-privileged code execution and bpf system-call access are required; successful exploitation enables root access and container escape.
The record
- CVE
- CVE-2021-31440
- Published
- May 21, 2021
- Updated
- Aug 3, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-682, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 21, 2021CVE publishedPublication date reported by the CVE source.
- Aug 3, 2024Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=5.11.15
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Public exploit references
- CVE-2021-31440: An Incorrect Bounds Calculation in the Linux Kernel eBPF Verifierproof of concept · demonstrated
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
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Your stack
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