#VU50430 Incorrect Regular Expression in Jinja - CVE-2020-28493

Vulnerability identifier: #VU50430

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2020-28493

CWE-ID: CWE-185

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Jinja
Web applications / Modules and components for CMS

Vendor: The Pallets Projects

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to incorrect subpattern applied to untrusted input. A remote attacker can pass specially crafted data to the application and perform a regular expression DoS (ReDOS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Jinja: before 2.11.3

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External links
https://github.com/pallets/jinja/blob/ab81fd9c277900c85da0c322a2ff9d68a235b2e6/src/jinja2/utils.py%23L20
https://github.com/pallets/jinja/pull/1343
https://snyk.io/vuln/SNYK-PYTHON-JINJA2-1012994

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.