{"id":"AZL-48495","summary":"CVE-2024-43882 affecting package kernel for versions less than 5.15.167.1-1","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nexec: Fix ToCToU between perm check and set-uid/gid usage\n\nWhen opening a file for exec via do_filp_open(), permission checking is\ndone against the file's metadata at that moment, and on success, a file\npointer is passed back. Much later in the execve() code path, the file\nmetadata (specifically mode, uid, and gid) is used to determine if/how\nto set the uid and gid. However, those values may have changed since the\npermissions check, meaning the execution may gain unintended privileges.\n\nFor example, if a file could change permissions from executable and not\nset-id:\n\n---------x 1 root root 16048 Aug  7 13:16 target\n\nto set-id and non-executable:\n\n---S------ 1 root root 16048 Aug  7 13:16 target\n\nit is possible to gain root privileges when execution should have been\ndisallowed.\n\nWhile this race condition is rare in real-world scenarios, it has been\nobserved (and proven exploitable) when package managers are updating\nthe setuid bits of installed programs. Such files start with being\nworld-executable but then are adjusted to be group-exec with a set-uid\nbit. For example, \"chmod o-x,u+s target\" makes \"target\" executable only\nby uid \"root\" and gid \"cdrom\", while also becoming setuid-root:\n\n-rwxr-xr-x 1 root cdrom 16048 Aug  7 13:16 target\n\nbecomes:\n\n-rwsr-xr-- 1 root cdrom 16048 Aug  7 13:16 target\n\nBut racing the chmod means users without group \"cdrom\" membership can\nget the permission to execute \"target\" just before the chmod, and when\nthe chmod finishes, the exec reaches brpm_fill_uid(), and performs the\nsetuid to root, violating the expressed authorization of \"only cdrom\ngroup members can setuid to root\".\n\nRe-check that we still have execute permissions in case the metadata\nhas changed. It would be better to keep a copy from the perm-check time,\nbut until we can do that refactoring, the least-bad option is to do a\nfull inode_permission() call (under inode lock). It is understood that\nthis is safe against dead-locks, but hardly optimal.","modified":"2026-04-01T05:16:03.476656Z","published":"2024-08-21T01:15:12Z","upstream":["CVE-2024-43882"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-43882"}],"affected":[{"package":{"name":"kernel","ecosystem":"Azure Linux:2","purl":"pkg:rpm/azure-linux/kernel"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.15.167.1-1"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-48495.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H"}]}