Libarchive through 3.6.2 can cause directories to have world-writable permissions. The umask() call inside archive_write_disk_posix.c changes the umask of the whole process for a very short period of time; a race condition with another thread can lead to a permanent umask 0 setting. Such a race condition could lead to implicit directory creation with permissions 0777 (without the sticky bit), which means that any low-privileged local user can delete and rename files inside those directories.

In libarchive before 3.6.2, the software does not check for an error after calling calloc function that can return with a NULL pointer if the function fails, which leads to a resultant NULL pointer dereference. NOTE: the discoverer cites this CWE-476 remark but third parties dispute the code-execution impact: "In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution."

An improper link resolution flaw can occur while extracting an archive leading to changing modes, times, access control lists, and flags of a file outside of the archive. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to gain more privileges in a system.

An improper link resolution flaw while extracting an archive can lead to changing the access control list (ACL) of the target of the link. An attacker may provide a malicious archive to a victim user, who would trigger this flaw when trying to extract the archive. A local attacker may use this flaw to change the ACL of a file on the system and gain more privileges.

libarchive 3.4.1 through 3.5.1 has a use-after-free in copy_string (called from do_uncompress_block and process_block).