SB2021051015 - Privilege escalation in Linux kernel SCTP sockets
Published: May 10, 2021
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 security vulnerability.
1) Race condition (CVE-ID: CVE-2021-23133)
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a race condition in Linux kernel SCTP sockets (net/sctp/socket.c). If sctp_destroy_sock is called without
sock_net(sk)->sctp.addr_wq_lock then an element is removed from the
auto_asconf_splist list without any proper locking. This can be
exploited by a local user with network service privileges to escalate to
root or from the context of an unprivileged user directly if a
BPF_CGROUP_INET_SOCK_CREATE is attached which denies creation of some
SCTP socket.
Remediation
Install update from vendor's website.
References
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=b166a20b07382b8bc1dcee2a448715c9c2c81b5b
- https://www.openwall.com/lists/oss-security/2021/04/18/2
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PAEQ3H6HKNO6KUCGRZVYSFSAGEUX23JL/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/CUX2CA63453G34C6KYVBLJXJXEARZI2X/
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/XZASHZVCOFJ4VU2I3BN5W5EPHWJQ7QWX/