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GHSA-7774-7vr3-cc8j

HighCVSS 8.3 / 10
Published Aug 30, 2021·Last modified Mar 13, 2026
Affected Components(0)

No affected components available

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 istio-security-vulnerability-reports@googlegroups.com

Risk Scores
Base Score
8.3

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. The attacker needs the user to perform some action, like clicking a link. The impact is confined to the system where the vulnerability exists. There is a high impact on the confidentiality of the information. There is a high impact on the integrity of the data. There is a low impact on the availability of the system.

Threat Intelligence
7.6

Exploitation activity has been observed. Apply available patches or mitigations urgently.

EPSS
1.18%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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