In short
- CVE-2021-39155 is a HIGH (CVSS 7.5) vulnerability affecting istio.io/istio, istio (istio).
- Chance of exploitation in the next 30 days (EPSS): 1.2%, higher than 69.2% of all vulnerabilities.
- Fix: update to 1.10.4, 1.11.1, 1.9.8 or later.
| Package | Affected versions | Patched versions |
|---|
| istio.io/istio Go | ≥ 1.10.0, < 1.10.4≥ 1.11.0, < 1.11.1< 1.9.8
| 1.10.41.11.11.9.8
|
| istio | ≥ 1.10.0, < 1.10.4≥ 1.11.0, < 1.11.1< 1.9.8
| 1.10.41.11.11.9.8
|
Description
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
- Istio 1.11.1 and above
- Istio 1.10.4 and above
- Istio 1.9.8 and above
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]
NVD description
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.
More vulnerabilities in istio.io/istio
See all →Running one of these products? Scan your site to see whether it exposes a vulnerable version.
Scan my site free