CVE-2020-10711

Published: 12 May 2020

A NULL pointer dereference flaw was found in the Linux kernel's SELinux subsystem in versions before 5.7. This flaw occurs while importing the Commercial IP Security Option (CIPSO) protocol's category bitmap into the SELinux extensible bitmap via the' ebitmap_netlbl_import' routine. While processing the CIPSO restricted bitmap tag in the 'cipso_v4_parsetag_rbm' routine, it sets the security attribute to indicate that the category bitmap is present, even if it has not been allocated. This issue leads to a NULL pointer dereference issue while importing the same category bitmap into SELinux. This flaw allows a remote network user to crash the system kernel, resulting in a denial of service.

From the Ubuntu security team

Matthew Sheets discovered that the SELinux network label handling implementation in the Linux kernel could be coerced into de-referencing a NULL pointer. A remote attacker could use this to cause a denial of service (system crash).

Priority

Low

CVSS 3 base score: 5.9

Status

Notes

SELinux is not the default MAC used in Ubuntu

References

• https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-10711
• https://www.openwall.com/lists/oss-security/2020/05/12/2
• https://lore.kernel.org/netdev/07d99ae197bfdb2964931201db67b6cd0b38db5b.1589276729.git.pabeni@redhat.com/T/#u
• https://ubuntu.com/security/notices/USN-4411-1
• https://ubuntu.com/security/notices/USN-4412-1
• https://ubuntu.com/security/notices/USN-4413-1
• https://ubuntu.com/security/notices/USN-4414-1
• https://ubuntu.com/security/notices/USN-4419-1
• NVD
• Launchpad
• Debian