#VU50814 Input validation error in Django - CVE-2021-23336

Vulnerability identifier: #VU50814

Vulnerability risk: Medium

CVSSv4.0: 2.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2021-23336

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Django
Web applications / CMS

Vendor: Django Software Foundation

Description

The vulnerability allows a remote attacker to perform web cache spoofing attack.

The vulnerability exists due to insufficient validation of user-supplied input in django.utils.http.limited_parse_qsl() when parsing strings with a semicolon (";"). A remote attacker can pass specially crafted data to the application and perform a spoofing attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Django: 2.2 - 2.2.18, 3.0 - 3.1.6

---

External links
https://github.com/python/cpython/pull/24297
https://snyk.io/blog/cache-poisoning-in-popular-open-source-packages/
https://snyk.io/vuln/SNYK-UPSTREAM-PYTHONCPYTHON-1074933
https://www.djangoproject.com/weblog/2021/feb/19/security-releases/

---

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.