#VU53523 Improper Authorization in Istio - CVE-2021-31921

Vulnerability identifier: #VU53523

Vulnerability risk: High

CVSSv4.0: 8.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-31921

CWE-ID: CWE-285

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Istio
Web applications / Other software

Vendor: Istio

Description

The vulnerability allows a remote attacker to bypass authorization procedure.

The vulnerability exists due to a logic issue when the istio gateway is configured with TLS mode `AUTO_PASSTHROUGH`. A remote non-authenticated attacker can bypass authorization checks and gain unauthorized access to services in the cluster.

Successful exploitation of the vulnerability may allow an attacker to compromise the affected system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Istio: 0.1 - 0.1.6, 0.2 - 0.2.12, 0.3 - 0.3.0, 0.4 - 0.4.0, 0.5 - 0.5.1, 0.6 - 0.6.0, 0.7 - 0.7.1, 0.8 - 0.8.0, 1.0 - 1.0.9, 1.1 - 1.10.0, 1.2 - 1.2.10, 1.3 - 1.3.8, 1.4 - 1.4.10, 1.5.0 - 1.5.10, 1.6.0 - 1.6.14, 1.7.0 - 1.7.8, 1.8.0 - 1.8.5, 1.9.0 - 1.9.4

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External links
https://istio.io/latest/news/security/istio-security-2021-006/

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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.