CVE-2021-20277: High severity samba vulnerability
A flaw was found in Samba's libldb. Multiple, consecutive leading spaces in an LDAP attribute can lead to an out-of-bounds memory write, leading to a crash of the LDAP server process handling the request. The highest threat from this vulnerability is to system availability.
Other sources
As per upstream:
A string in an LDAP attribute that contains multiple consecutive leading spaces can lead to a memmove() of out of bounds memory in ldbhandlerfold().
ldbhandlerfold() is used by case insensitive strings - that is most string attributes - in Active Directory.
As the search expression is normalised prior to matching any potential objects this in turn may crash the LDAP server process handling the request. It may be possible to leak the out of bounds memory by matching against it, but this is thought to be unlikely.
— Red Hat
Affected Software
Event History
Frequently Asked Questions
What is CVE-2021-20277?
CVE-2021-20277 is a vulnerability found in Samba's libldb that allows multiple consecutive leading spaces in an LDAP attribute, leading to an out-of-bounds memory write and a crash of the LDAP server process.
What is the severity of CVE-2021-20277?
The severity of CVE-2021-20277 is high with a CVSS score of 7.5.
What software is affected by CVE-2021-20277?
Samba versions between 4.0.0 and 4.12.13, 4.13.0 and 4.13.6, and 4.14.0 and 4.14.1 are affected. Debian Linux versions 9.0 and 10.0, Fedora versions 32, 33, and 34 are also affected.
What is the highest threat from CVE-2021-20277?
The highest threat from CVE-2021-20277 is to system availability.
How do I fix the CVE-2021-20277 vulnerability?
To fix the CVE-2021-20277 vulnerability, update Samba to versions 4.13.7, 4.14.2, or 4.15.0. Or, apply the respective security updates for Debian Linux and Fedora.