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Security Advisories: MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTc3NzQtN3ZyMy1jYzhq

Authorization Policy Bypass Due to Case Insensitive Host Comparison

Impact

According to RFC 4343, Istio authorization policy should compare the hostname in the HTTP Host header in a case insensitive way, but currently the comparison is case sensitive. The Envoy proxy will route the request hostname in a case-insensitive way which means the authorization policy could be bypassed.

As an example, the user may have an authorization policy that rejects request with hostname "httpbin.foo" for some source IPs, but the attacker can bypass this by sending the request with hostname "Httpbin.Foo".

Patches

Workarounds

A Lua filter may be written to normalize Host header before the authorization check. This is similar to the Path normalization presented in the Security Best Practices guide.

References

More details can be found in the Istio Security Bulletin.

For more information

If you have any questions or comments about this advisory, please email us at [email protected]

Permalink: https://github.com/advisories/GHSA-7774-7vr3-cc8j
JSON: https://advisories.ecosyste.ms/api/v1/advisories/MDE2OlNlY3VyaXR5QWR2aXNvcnlHSFNBLTc3NzQtN3ZyMy1jYzhq
Source: GitHub Advisory Database
Origin: Unspecified
Severity: High
Classification: General
Published: over 2 years ago
Updated: 12 months ago


CVSS Score: 8.3
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:L

Identifiers: GHSA-7774-7vr3-cc8j, CVE-2021-39155
References: Repository: https://github.com/istio/istio
Blast Radius: 18.0

Affected Packages

go:istio.io/istio
Dependent packages: 119
Dependent repositories: 149
Downloads:
Affected Version Ranges: = 1.11.0, >= 1.10.0, < 1.10.4, < 1.9.8
Fixed in: 1.11.1, 1.10.4, 1.9.8
All affected versions:
All unaffected versions: