SB2021060425 - Privilege escalation in Linux kernel io_uring
Published: June 4, 2021 Updated: October 13, 2022
Security Bulletin ID
SB2021060425
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Local access
Highest impact
Code execution
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Out-of-bounds write (CVE-ID: CVE-2021-3491)
CWE-ID: CWE-787 - Out-of-bounds write
CVSSv4: 8.5 [CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N]
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to the io_uring subsystem in the Linux kernel allowed the MAX_RW_COUNT limit to be bypassed in the PROVIDE_BUFFERS
operation, which led to negative values being used in mem_rw when reading
/proc/<PID>/mem. A local user can trigger a heap overflow and execute arbitrary code with elevated privileges.
Remediation
Install update from vendor's website.