CVE-2021-27556
About
The Cron job tab in EasyCorp ZenTao 12.5.3 allows remote attackers (who have admin access) to execute arbitrary code by setting the type parameter to System.
Rainforest analyst review
In EasyCorp ZenTao, an attacker with admin access can set a cron job's type parameter to System and thereby run arbitrary code on the server. The vector's high-privilege requirement is the whole story: this is a privileged feature being abused, reachable only by someone who already holds admin.
Because it demands admin access up front, this is effectively post-authentication functionality abuse rather than a break-in. Its realistic use is by an insider or by an attacker who has already obtained admin credentials through some other means, making it a chain component rather than an initial vector.
We rank it down given the PR:H precondition and treat it as an access-control and inventory matter: know which ZenTao instances are deployed and at what version, and tightly restrict and monitor who can reach admin. The control that actually matters here is keeping the admin role out of untrusted hands, since that's the only thing this exploit needs.
References
Related CVEs
Frequently asked questions
What is CVE-2021-27556?
The Cron job tab in EasyCorp ZenTao 12.5.3 allows remote attackers (who have admin access) to execute arbitrary code by setting the type parameter to System.
How severe is CVE-2021-27556?
CVE-2021-27556 carries a CVSS 3.1 base score of 7.2, rated high. On the Rainforest Risk Index — which weighs the severity alongside how easy the flaw is to reach and how broad its impact is — it scores 76 out of 100, in the high band.
How is CVE-2021-27556 exploited?
According to the CVSS vector (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H): attack vector Network, attack complexity Low, privileges required High, user interaction None. Impact on confidentiality High, integrity High and availability High.
Which products are affected by CVE-2021-27556?
Public advisories list the following as affected: zentao. Check the references on this page for the exact versions each vendor confirms.
How do I fix CVE-2021-27556?
Apply the fix the vendor published — the references on this page link to the primary advisories and patches. When patching can't happen right away, reduce the exposure of the affected component and watch it for exploitation attempts. Rainforest customers see this vulnerability correlated to their own assets and prioritized by real exposure, not by score alone.
Empower Your Security Strategy with Rainforest
Discover vulnerabilities early, prioritize critical threats, and protect what truly matters. Rainforest streamlines your security operations, saving you time and reducing costs, so you can focus on what drives your business forward.