SB2021081901 - Privilege escalation in Linux kernel
Published: August 19, 2021
Security Bulletin ID
SB2021081901
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 security vulnerability.
1) Out-of-bounds write (CVE-ID: CVE-2021-3490)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a boundary error when processing untrusted input in bpf. The eBPF ALU32 bounds tracking for bitwise ops (AND, OR and XOR) in the
Linux kernel did not properly update 32-bit bounds, which could be
turned into out of bounds reads and writes in the Linux kernel and
therefore, arbitrary code execution. A local user can run a specially crafted program to trigger an out-of-bounds write and execute arbitrary code with elevated privileges.
Remediation
Install update from vendor's website.
References
- https://ubuntu.com/security/notices/USN-4949-1
- https://www.zerodayinitiative.com/advisories/ZDI-21-606/
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
- https://ubuntu.com/security/notices/USN-4950-1
- https://www.openwall.com/lists/oss-security/2021/05/11/11
- https://security.netapp.com/advisory/ntap-20210716-0004/