Vulnerability identifier: #VU50389

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-36221

CWE-ID: CWE-191

Exploitation vector: Network

Exploit availability: No

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

Vendor: OpenLDAP.org

Description

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

The vulnerability exists due to integer underflow within the serialNumberAndIssuerCheck() function in schema_init.c. A remote attacker can send a specially crafted request to the affected application, trigger an integer underflow and crash the slapd.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

OpenLDAP: 2.4.3 - 2.4.56

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External links
http://bugs.openldap.org/show_bug.cgi?id=9404
http://bugs.openldap.org/show_bug.cgi?id=9424
http://git.openldap.org/openldap/openldap/-/commit/38ac838e4150c626bbfa0082b7e2cf3a2bb4df31
http://git.openldap.org/openldap/openldap/-/commit/58c1748e81c843c5b6e61648d2a4d1d82b47e842
http://git.openldap.org/openldap/openldap/-/tags/OPENLDAP_REL_ENG_2_4_57
http://lists.debian.org/debian-lts-announce/2021/02/msg00005.html
http://www.debian.org/security/2021/dsa-4845

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

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