#VU54077 Resource exhaustion in urllib3 - CVE-2021-33503

Vulnerability identifier: #VU54077

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-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

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

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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.