Vulnerability in Carbone software

CERT Polska has received a report about vulnerability in Carbone software and participated in coordination of its disclosure.

The vulnerabilityCVE-2026-18929: Carbone is vulnerable to Denial of Service due to lack of protection against zip bombs when processing .docx files. The library uses yazl for zip decompression without validating entry sizes, allowing an attacker to supply a malicious .docx file containing a zip bomb that decompresses to a significantly larger size, causing excessive memory consumption and crashing the application server.

The issue was fixed in versions: 3.8.2, 4.26.3 and 5.4.4. The fix is available across all distribution types.

We thank Mikołaj Dąbek and Kamil Solecki for the responsible vulnerability report.