CVE-2020-28493

What is this vulnerability?

CVE-2020-28493 is categorized as a critical Memory Corruption Vulnerability flaw. Based on our vulnerability intelligence, this issue occurs when the application fails to securely handle untrusted data boundaries.

This affects the package jinja2 from 0.0.0 and before 2.11.3. The ReDOS vulnerability of the regex is mainly due to the sub-pattern [a-zA-Z0-9._-]+.[a-zA-Z.

This architectural defect enables adversaries to bypass intended security controls, directly manipulating the application's execution state or data layer. Immediate strategic intervention is required.

Risk Assessment

Impact on Systems

✅ Remote Code Execution: Adversaries may execute arbitrary code by overwriting memory regions.

✅ Denial of Service: Memory corruption often leads to unrecoverable application crashes.

✅ Information Disclosure: Out-of-bounds reads can expose adjacent memory containing sensitive data.

How to fix this issue?

Implement the following strategic mitigations immediately to eliminate the attack surface.

1. Memory-Safe Languages When possible, migrate parsing logic to memory-safe languages like Rust or Go.

2. Compiler Protections Ensure the binary is compiled with ASLR, DEP/NX, Stack Canaries, and RELRO.

3. Fuzz Testing Implement continuous fuzzing with AddressSanitizer (ASan) in the CI/CD pipeline.

Vulnerability Signature

// Generic Memory Corruption Vector (C/C++)
void process_input(char *user_data, size_t size) \{
    char buffer[256];
    // DANGEROUS: Unbounded memory operation
    memcpy(buffer, user_data, size); // size may exceed 256
    
    // SECURED: Bound-checked operation
    if (size \> sizeof(buffer)) \{
        size = sizeof(buffer);
    \}
    memcpy(buffer, user_data, size);
\}

References and Sources

• NVD — CVE-2020-28493
• MITRE — CVE-2020-28493
• Binary Analysis Vulnerabilities
• OSV.dev Database