Executive brief
SzafirHost, a component used for managing electronic signatures, contains a vulnerability in how it verifies downloaded software updates or components. An attacker could trick the system into running malicious code by disguising it within a file that appears to have a valid digital signature. If exploited, this could allow an attacker to gain full control over the system, potentially compromising sensitive signing keys or disrupting business operations.
Technical details
SzafirHost exhibits a 'signature wrapping' or 'ZIP/JAR ambiguity' vulnerability. The application verifies the digital signature of downloaded JAR files using the JarInputStream class, which processes the file sequentially from the beginning. However, it subsequently loads classes using JarFile or URLClassLoader, which locate files by reading the Central Directory at the end of the ZIP archive. An attacker can craft a 'chameleon' file that contains a legitimate, signed JAR at the start but a malicious ZIP structure at the end. This causes the signature check to pass while the JVM executes the attacker's malicious classes. This issue is resolved in version 1.2.1.
Affected products
- Krajowa Izba Rozliczeniowa (KIR) SzafirHost All versions prior to 1.2.1
Timeline
- 2026-05-15: advisory: Advisory published by CERT.PL and NVD
- 2026-05-15: patched: Fixed in version 1.2.1