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The CVE-2026-25526 vulnerability in Jinjava involves multiple sandbox bypass flaws enabling remote code execution. The ForTag class fails to enforce JinjavaBeanELResolver restrictions during property iteration. It uses Introspector.getBeanInfo() to access bean properties and invokes getter methods via PropertyDescriptor.getReadMethod() without security checks. This allows attackers to access arbitrary getter methods on template context objects. Simultaneously, the sandbox’s type allowlist is bypassed using ObjectMapper for JSON deserialization. Attackers can instantiate ObjectMapper, enable default typing, and create prohibited classes like JinjavaELContext and JinjavaConfig. These bypasses permit reading server files such as /etc/passwd and executing arbitrary Java code, compromising the system.
Platform: Jinjava
Version: Prior to 2.8.3
Vulnerability: Sandbox Bypass RCE
Severity: Critical
date: 2026-01-01
Prediction: Patched in 2026
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Bash commands:
curl -v target.com
java -jar scanner.jar
python3 test_cve.py
Codes:
{% for prop in object %}
{{ prop.getReadMethod().invoke() }}
{% endfor %}
ObjectMapper mapper = new ObjectMapper();
mapper.enableDefaultTyping();
JinjavaConfig config = mapper.readValue(json, JinjavaConfig.class);
How Exploit:
Attacker crafts malicious Jinja template exploiting ForTag bypass to access getters. Uses ObjectMapper deserialization to instantiate restricted classes. Executes file read or code execution via crafted payloads.
Protection from this CVE
Upgrade to Jinjava 2.8.3. Implement strict sandbox policies. Validate all template inputs. Restrict ObjectMapper usage.
Impact:
Critical RCE risk. Arbitrary file access. Full system compromise. Sandbox integrity broken.
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Sources:
Reported By: github.com
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