Kernel code execution via oversized io_uring buffers
Published Jun 4, 2021 · Updated Sep 16, 2024
Heap overflow in affected Linux Kernel builds allows local users to execute arbitrary code in the kernel through io_uring buffers. The io_add_buffers function accepted a user-supplied PROVIDE_BUFFERS length above MAX_RW_COUNT and stored it as a signed buffer length, producing a negative size during reads from a process's /proc/PID/mem file. Exploitation requires low-privileged local code execution and grants kernel-context code execution with control of the host.
Summary
What happened
Heap overflow in affected Linux Kernel builds allows local users to execute arbitrary code in the kernel through io_uring buffers. The io_add_buffers function accepted a user-supplied PROVIDE_BUFFERS length above MAX_RW_COUNT and stored it as a signed buffer length, producing a negative size during reads from a process's /proc/PID/mem file. Exploitation requires low-privileged local code execution and grants kernel-context code execution with control of the host.
The record
- CVE
- CVE-2021-3491
- Published
- Jun 4, 2021
- Updated
- Sep 16, 2024
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- CWE-787, CWE-131, T1068
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- Jun 4, 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=linux-5.10.y <v5.10.37
- Affected versionversion=linux-5.11.y <v5.11.21
- Affected versionversion=linux-5.12.y <v5.12.4
- Affected versionversion=trunk <v5.13-rc4
- Affected versionversion=v5.7-rc1 <5.7*
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.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
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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