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CVE-2021-39155

Istio is an open source platform for providing a uniform way to integrate microservices, manage traffic flow across microservices, enforce policies and aggregate telemetry data. According to [RFC 4343](https://datatracker.ietf.org/doc/html/rfc4343), 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 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 are available in Istio 1.11.1, Istio 1.10.4 and Istio 1.9.8. As a work around 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](https://istio.io/latest/docs/ops/best-practices/security/#case-normalization) guide.

Published

2021-08-24T23:15:07.093

Last Modified

2024-11-21T06:18:44.323

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 8.3 (HIGH)

CVSSv2 Vector

AV:N/AC:L/Au:N/C:P/I:N/A:N

  • Access Vector: NETWORK
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: NONE
  • Availability Impact: NONE
Exploitability Score

10.0

Impact Score

2.9

Weaknesses
  • Type: Secondary
    CWE-178
  • Type: Primary
    CWE-178
    CWE-863
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application istio istio < 1.9.8 Yes
Application istio istio < 1.10.4 Yes
Application istio istio < 1.11.1 Yes
References