Denial of service in OpenLDAP

Published: 2021-02-17 | Updated: 2021-03-23
Risk Medium
Patch available YES
Number of vulnerabilities 1
CVE-ID CVE-2021-27212
Exploitation vector Network
Public exploit N/A
Vulnerable software
Server applications / Directory software, identity management


Security Bulletin

This security bulletin contains information about 1 vulnerabilities.

Updated: 23.03.2021

Changed bulletin status to patched.

1) Reachable Assertion

EUVDB-ID: #VU50779

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-2021-27212

CWE-ID: CWE-617 - Reachable Assertion

Exploit availability: No


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

The vulnerability exists due to a reachable assertion when processing LDAP packets within the issuerAndThisUpdateCheck() function in  schema_init.c. A remote attacker can send a specially crafted packet with a short timestamp to the slapd and perform a denial of service (DoS) attack.


Install update from vendor's website.

Vulnerable software versions

OpenLDAP: 2.4 - 2.4.57

External links

Q & A

Can this vulnerability be exploited remotely?

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

How the attacker can exploit this vulnerability?

The attacker would have to send a specially crafted request to the affected application in order to exploit this vulnerability.

Is there known malware, which exploits this vulnerability?

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