Red Hat Enterprise Linux 8 update for samba

1) Out-of-bounds read

EUVDB-ID: #VU52748

Risk: Medium

CVSSv3.1: 4 [CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-20254

CWE-ID: CWE-125 - Out-of-bounds read

Exploit availability: No

Description

The vulnerability allows a remote user to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition when mapping Windows group identities (SIDs) into unix group identities (gids), which resulted into negative idmap cache entries created in the Samba server process token. An attacker who can manage to trigger the vulnerability can crash the Samba server or potentially perform unauthorized actions on the system.

Mitigation

Install updates from vendor's website.

Vulnerable software versions

Red Hat CodeReady Linux Builder for IBM z Systems - Extended Update Support: 8.4

Red Hat CodeReady Linux Builder for Power, little endian - Extended Update Support: 8.4

Red Hat CodeReady Linux Builder for ARM 64 - Extended Update Support: 8.4

Red Hat CodeReady Linux Builder for x86_64 - Extended Update Support: 8.4

Red Hat Enterprise Linux Server for x86_64 - Update Services for SAP Solutions: 8.4

Red Hat CodeReady Linux Builder for IBM z Systems: 8.0

Red Hat Enterprise Linux Server for Power LE - Update Services for SAP Solutions: 8.4

Red Hat Enterprise Linux Server - TUS: 8.4

Red Hat Enterprise Linux for Power, little endian - Extended Update Support: 8.4

Red Hat Enterprise Linux for IBM z Systems - Extended Update Support: 8.4

Red Hat Enterprise Linux Server - AUS: 8.4

Red Hat Enterprise Linux for x86_64 - Extended Update Support: 8.4

Red Hat Enterprise Linux for ARM 64 - Extended Update Support: 8.4

samba (Red Hat package): 4.13.3-3.el8

Red Hat CodeReady Linux Builder for ARM 64: 8.0

Red Hat CodeReady Linux Builder for Power, little endian: 8.0

Red Hat CodeReady Linux Builder for x86_64: 8.0

Red Hat Enterprise Linux for ARM 64: 8

Red Hat Enterprise Linux for Power, little endian: 8

Red Hat Enterprise Linux for IBM z Systems: 8

Red Hat Enterprise Linux for x86_64: 8.0

External links

http://access.redhat.com/errata/RHSA-2021:4058

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the local network (LAN).

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.