It was discovered that Adminer did not escape data in the history parameter of the default URI. A remote attacker could possibly use this issue to perform cross-site scripting (XSS) attacks. This issue only affected Ubuntu 20.04 ESM. (CVE-2020-35572)
Adam Crosser and Brian Sizemore discovered that Adminer incorrectly handled redirection requests to internal servers. An unauthenticated remote attacker could possibly use this to perform a server-side request forgery attack and expose sensitive information. (CVE-2021-21311)
It was discovered that Adminer was incorrectly escaping data in the doc_link function. A remote attacker could possibly use this issue to perform cross-site scripting (XSS) attacks. This issue only affected Ubuntu 18.04 ESM and Ubuntu 20.04 ESM. (CVE-2021-29625)