Vulnerability identifier: #VU54077

Vulnerability 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-2021-33503

CWE-ID: CWE-400

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
urllib3
Other software / Other software solutions

Vendor: shazow (Andrey Petrov)

Description

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

The vulnerability exists due to improper input validation in urllib3 when processing URL with multiple "@" characters in the authority component. A remote attacker can trigger resource exhaustion and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

urllib3: 0.3 - 1.26.4

---

External links
http://github.com/urllib3/urllib3/security/advisories/GHSA-q2q7-5pp4-w6pg
http://github.com/urllib3/urllib3/commit/2d4a3fee6de2fa45eb82169361918f759269b4ec

---

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.