CVE-2025-27516 is a vulnerability in the Jinja template engine affecting Red Hat Developer Hub (RHDH) 1.4. The flaw arises from an oversight in the sandboxed environment where the |attr filter can be exploited to access a string's plain format method, bypassing sandbox restrictions and enabling arbitrary Python code execution. Exploitation requires control over template content, which depends on the application context. This vulnerability affects applications that process untrusted templates and can lead to full compromise of the affected system's integrity, confidentiality, and availability. Red Hat classifies this vulnerability as important/high severity and has not yet released a patch for RHDH 1.4.3. The vulnerability is tracked under Red Hat advisory RHSA-2025:3595 and is related to CWE-1336 and CWE-347.

An attacker who can control the content of a Jinja template in Red Hat Developer Hub 1.4 can bypass the sandbox protections and execute arbitrary Python code. This can lead to a complete compromise of the system's integrity, confidentiality, and availability. The vulnerability requires local or application-level control over template content and user interaction to trigger. No known exploits in the wild have been reported. The impact is significant for applications that allow execution of untrusted templates.

No official fix or patch is currently available for Red Hat Developer Hub 1.4.3 as per the vendor advisory RHSA-2025:3595. Users should monitor Red Hat's security advisories for updates regarding patches or fixes. Until a fix is released, users should avoid executing untrusted templates or restrict template content control to trusted users only. Applying mitigations depends on the specific application context. Red Hat provides support channels for customers to discuss mitigation options with technical account managers.