CVE-2021-20254

A flaw was found in samba. The Samba smbd file server must map Windows group identities (SIDs) into unix group ids (gids). The code that performs this had a flaw that could allow it to read data beyond the end of the array in the case where a negative cache entry had been added to the mapping cache. This could cause the calling code to return those values into the process token that stores the group membership for a user. The highest threat from this vulnerability is to data confidentiality and integrity.

• CWE-125

• https://bugzilla.redhat.com/show_bug.cgi?id=1949442Issue Tracking, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00023.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/
• https://security.gentoo.org/glsa/202105-22Third Party Advisory
• https://security.netapp.com/advisory/ntap-20210430-0001/Third Party Advisory
• https://www.samba.org/samba/security/CVE-2021-20254.htmlVendor Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=1949442Issue Tracking, Third Party Advisory
• https://lists.debian.org/debian-lts-announce/2021/05/msg00023.htmlMailing List, Third Party Advisory
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3EP2VJ73OVBPVSOSTVOMGIEQA3MWF6F7/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZAF6L2M6CNAJ2YYYGXPWETTW5YLCWTVT/
• https://security.gentoo.org/glsa/202105-22Third Party Advisory
• https://security.netapp.com/advisory/ntap-20210430-0001/Third Party Advisory
• https://www.samba.org/samba/security/CVE-2021-20254.htmlVendor Advisory

Published

May 5, 2021

Last Modified

Jun 17, 2026

Status

Modified

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