SB2021052510 - Authorization bypass in Istio

Description

This security bulletin contains information about 2 vulnerabilities.

1) Improper Authorization (CVE-ID: CVE-2021-31921)

CWE-ID: CWE-285 - Improper Authorization

CVSSv4: 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

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.

2) Improper Authorization (CVE-ID: CVE-2021-31920)

CWE-ID: CWE-285 - Improper Authorization

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

The vulnerability allows a remote attacker to bypass authorization checks.

The vulnerability exists due to improper input validation when processing HTTP request path with multiple slashes or escaped slash characters (%2F or %5C). A remote attacker can bypass Istio authorization policy when path based authorization rules are used.

Remediation

Install update from vendor's website.

References

• https://istio.io/latest/news/security/istio-security-2021-006/
• https://istio.io/latest/news/security/istio-security-2021-005/