Vulnerability identifier: #VU51701

Vulnerability risk: Medium

CVSSv3.1: 5.7 [CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-20277

CWE-ID: CWE-125

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Samba
Server applications / Directory software, identity management

Vendor: Samba

Description

The vulnerability allows a remote user to perform a denial of service (DoS) attack.

The vulnerability exists due to a boundary condition in ldb_handler_fold() function when processing multiple consecutive leading spaces within LDAP query. A remote user can send a specially crafted LDAP query, trigger out-of-bounds read error and crash the LDAP server.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Samba: 4.14.0, 4.13.0 - 4.13.5, 4.12.0 - 4.12.12, 4.11.0 - 4.11.17, 4.10.0 - 4.10.18, 4.9.0 - 4.9.18, 4.8.0 - 4.8.12, 4.7.0 - 4.7.12, 4.6.0 - 4.6.16, 4.5.0 - 4.5.16, 4.4.0 - 4.4.16, 4.3.0 - 4.3.13, 4.2.0 - 4.2.14, 4.1.0 - 4.1.23, 4.0.0 - 4.0.26

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External links
http://www.samba.org/samba/security/CVE-2021-20277.html

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

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