CVE-2022-30333

RARLAB's UnRAR command-line decompression tool on Linux and UNIX, in versions before 6.12, contains a directory traversal flaw (CWE-22, with symlink-based path confusion per CWE-59) that lets a crafted RAR archive write files to arbitrary filesystem locations during an extract/unpack operation. It is triggered whenever an application passes an attacker-supplied archive to unrar, most prominently Zimbra Collaboration Suite, which unpacked RAR attachments from incoming email, enabling pre-authentication attacks against webmail tracked separately as CVE-2022-41352. By planting files at chosen paths — for example writing an SSH key to ~/.ssh/authorized_keys or dropping a web shell under a web root — an attacker can escalate an arbitrary file write into code execution on the server, requiring no privileges or user interaction per the CVSS vector. Only the Linux/UNIX UnRAR utility is affected; WinRAR and RAR for Android are not. The flaw is under active exploitation: CISA added it to the Known Exploited Vulnerabilities catalog on 2022-08-09 with known ransomware use, public PoCs exist, and EPSS estimates a ~99% probability of exploitation within 30 days.

What to do: Upgrade UnRAR to 6.12 or later on all Linux and UNIX systems and apply Debian's patched unrar package; Zimbra administrators should apply Zimbra's released security patches, which ship the fixed UnRAR. As an interim mitigation, restrict or monitor services that automatically extract RAR archives from untrusted sources, and hunt for indicators such as unexpected ~/.ssh/authorized_keys entries, planted symlinks, or web shells under web roots. Because the flaw is on CISA's KEV list with known ransomware use, treat patching as time-critical.