UBUNTU-CVE-2021-3864

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UBUNTU-CVE-2021-3864

Summary:

Details: A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.

References: https://ubuntu.com/security/CVE-2021-3864, https://www.openwall.com/lists/oss-security/2021/10/20/2, https://lore.kernel.org/all/[email protected], https://lore.kernel.org/lkml/[email protected], https://lore.kernel.org/all/[email protected]/, https://www.cve.org/CVERecord?id=CVE-2021-3864