Denial of service in Pallets Jinja

1) Incorrect Regular Expression

EUVDB-ID: #VU50430

Risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2020-28493

CWE-ID: CWE-185 - Incorrect Regular Expression

Exploit availability: No

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

External links

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

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.