SimpleEval is a lightweight library that evaluates Python expressions supplied by users. Prior to version 1.0.5, its sandbox allowed objects—such as modules—that were passed in as names to be exposed as attributes within the evaluation context. This flaw means that an attacker can reference potentially dangerous modules or functions that the library itself deems disallowed, effectively permitting execution of arbitrary code with the privileges of the host application. The weakness is reflected in CWE‑915 (Code Injection) and CWE‑94 (Code Injection via Dynamic Untrusted Input).

The vulnerability affects the danthedeckie:simpleeval package for all releases before 1.0.5. Any installation of SimpleEval older than 1.0.5 that receives untrusted expressions is vulnerable.

The CVE has a CVSS score of 8.7, indicating high severity, while the EPSS score is below 1% and the flaw is not listed in the CISA KEV catalog, suggesting a relatively low probability of widespread exploitation. The likely attack vector is an application embedding SimpleEval and processing user‑supplied expressions; from that point an attacker can craft an expression that accesses disallowed modules or functions, leading to remote code execution. The attacker does not need additional privileges beyond those of the running application.