CVE-2020-28493 : Security Advisory and Response

This CVE-2020-28493 article provides insights into a Regular Expression Denial of Service (ReDoS) vulnerability affecting the jinja2 package.

Understanding CVE-2020-28493

This section delves into the details of the CVE-2020-28493 vulnerability.

What is CVE-2020-28493?

CVE-2020-28493 is a ReDoS vulnerability in the jinja2 package versions 0.0.0 to 2.11.3 due to the

_punctuation_re regex

operator's use of multiple wildcards.

The Impact of CVE-2020-28493

The vulnerability has a CVSS base score of 5.3 (Medium severity) and affects systems with network accessibility, potentially leading to denial of service.

Technical Details of CVE-2020-28493

This section provides technical insights into the CVE-2020-28493 vulnerability.

Vulnerability Description

The vulnerability arises from the

_punctuation_re regex

operator in jinja2, allowing for ReDoS attacks due to the use of multiple wildcards.

Affected Systems and Versions

Affected versions: 0.0.0 to 2.11.3

Exploitation Mechanism

The vulnerability can be exploited by crafting malicious input that triggers excessive backtracking in the regex engine.

Mitigation and Prevention

Explore the mitigation strategies to address CVE-2020-28493.

Immediate Steps to Take

Avoid using the urlize filter and opt for Markdown to format user content.
Implement request timeouts and restrict process memory usage to mitigate the risk.

Long-Term Security Practices

Regularly update the jinja2 package to patched versions.
Monitor security advisories for any new developments related to this vulnerability.

Patching and Updates

Apply patches provided by the vendor to fix the ReDoS vulnerability in jinja2.