Root privilege escalation via s390 JIT miscompilation
Published Feb 18, 2022 · Updated Aug 3, 2024
Privilege escalation in the Linux Kernel s390 eBPF JIT before 5.15-rc3 allows local users to gain root privileges through crafted BPF code. The bpf_jit_insn code miscompiles constant subtraction, elides required 32-bit zero-extension, and computes branch displacements from a stale code-size assumption. Exploitation requires local low-privileged access to load BPF programs on an s390x system with the JIT enabled; successful verifier bypass grants root privileges.
Summary
What happened
Privilege escalation in the Linux Kernel s390 eBPF JIT before 5.15-rc3 allows local users to gain root privileges through crafted BPF code. The bpf_jit_insn code miscompiles constant subtraction, elides required 32-bit zero-extension, and computes branch displacements from a stale code-size assumption. Exploitation requires local low-privileged access to load BPF programs on an s390x system with the JIT enabled; successful verifier bypass grants root privileges.
The record
- CVE
- CVE-2021-20320
- Published
- Feb 18, 2022
- Updated
- Aug 3, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-200, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Feb 18, 2022CVE 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?
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- Affected versionversion=kernel 5.15 rc3
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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