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.
The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Libarchive | Libarchive | * | 3.6.2 (including) |
| Libarchive | Ubuntu | bionic | * |
| Libarchive | Ubuntu | devel | * |
| Libarchive | Ubuntu | esm-infra-legacy/trusty | * |
| Libarchive | Ubuntu | esm-infra/bionic | * |
| Libarchive | Ubuntu | esm-infra/focal | * |
| Libarchive | Ubuntu | esm-infra/xenial | * |
| Libarchive | Ubuntu | focal | * |
| Libarchive | Ubuntu | jammy | * |
| Libarchive | Ubuntu | kinetic | * |
| Libarchive | Ubuntu | lunar | * |
| Libarchive | Ubuntu | trusty | * |
| Libarchive | Ubuntu | trusty/esm | * |
| Libarchive | Ubuntu | xenial | * |
A race condition occurs within concurrent environments, and it is effectively a property of a code sequence. Depending on the context, a code sequence may be in the form of a function call, a small number of instructions, a series of program invocations, etc. A race condition violates these properties, which are closely related:
A race condition exists when an “interfering code sequence” can still access the shared resource, violating exclusivity. The interfering code sequence could be “trusted” or “untrusted.” A trusted interfering code sequence occurs within the product; it cannot be modified by the attacker, and it can only be invoked indirectly. An untrusted interfering code sequence can be authored directly by the attacker, and typically it is external to the vulnerable product.