#VU56151 Improper Authorization in Istio - CVE-2021-39156

Vulnerability identifier: #VU56151

Vulnerability risk: High

CVSSv4.0: 6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber]

CVE-ID: CVE-2021-39156

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 checks.

The vulnerability exists due to insufficient authorization checks. A remote attacker can send a specially crafted HTTP request with #fragment in the path and bypass authorization on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Istio: 1.9.0 - 1.9.7, 1.10.0 - 1.11.0

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External links
https://istio.io/latest/news/security/istio-security-2021-008
https://github.com/istio/istio/security/advisories/GHSA-hqxw-mm44-gc4r

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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.