Kernel memory disclosure via incorrect mod32 truncation
Published Mar 23, 2021 · Updated Sep 16, 2024
Out-of-bounds access in the Linux Kernel eBPF verifier allows local users to read kernel memory through a crafted eBPF program. In kernel/bpf/verifier.c, the verifier models a 32-bit modulo-by-zero destination as truncated while the runtime leaves its upper bits unchanged, enabling unsafe verifier conclusions. Reaching the flaw requires permission to load eBPF programs, normally CAP_SYS_ADMIN or root unless unprivileged BPF is enabled; kernel-memory disclosure is established, but controllable writes are not.
Summary
What happened
Out-of-bounds access in the Linux Kernel eBPF verifier allows local users to read kernel memory through a crafted eBPF program. In kernel/bpf/verifier.c, the verifier models a 32-bit modulo-by-zero destination as truncated while the runtime leaves its upper bits unchanged, enabling unsafe verifier conclusions. Reaching the flaw requires permission to load eBPF programs, normally CAP_SYS_ADMIN or root unless unprivileged BPF is enabled; kernel-memory disclosure is established, but controllable writes are not.
The record
- CVE
- CVE-2021-3444
- Published
- Mar 23, 2021
- Updated
- Sep 16, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-681, CWE-125, CAPEC-540, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Mar 23, 2021CVE publishedPublication date reported by the CVE source.
- Sep 16, 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=5.10 <5.10.19
- Affected versionversion=5.11 <5.11.2
- Affected versionversion=5.4 <5.4.101
- Affected versionversion=trunk <5.12-rc1
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
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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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