A vulnerability was found in thinkgem JeeSite up to 5.12.1. This affects the function decodeUrl2 of the file common/src/main/java/com/jeesite/common/codec/EncodeUtils.java. The manipulation results in cross site scripting. It is possible to launch the attack remotely. The exploit has been made public and could be used. Upgrading to version 5.13.0 mitigates this issue. The patch is identified as 63773c97a56bdb3649510e83b66c16db4754965b. Upgrading the affected component is recommended.