Executive brief
libarchive is a widely-used library for reading and writing archive files (ZIP, TAR, ISO, etc.) used by many applications and systems. A flaw in its zisofs decompression logic can be triggered by a specially crafted ISO file, causing the application to crash and become temporarily unavailable. An attacker could distribute malicious ISO files to disrupt services relying on libarchive.
Technical details
An undefined behavior vulnerability exists in libarchive's zisofs decompression logic, caused by improper validation of the `pz_log2_bs` field read from ISO9660 Rock Ridge extensions. The vulnerability can be triggered by supplying a specially crafted ISO file with invalid field values. This leads to incorrect memory allocation calculations, causing application crashes and denial-of-service conditions. The flaw is reachable remotely via processing untrusted ISO files, with no authentication or user interaction required beyond opening the file. Patches addressing this validation issue are expected from the libarchive maintainers.
Affected products
- libarchive libarchive <UNKNOWN>
Timeline
- 2026-03-19: disclosed