7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:N/A:N
0.001 Low
EPSS
Percentile
46.8%
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”.
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.
More details can be found in the Istio Security Bulletin.
If you have any questions or comments about this advisory, please email us at [email protected]
CPE | Name | Operator | Version |
---|---|---|---|
istio.io/istio | eq | 1.11.0 | |
istio.io/istio | lt | 1.10.4 | |
istio.io/istio | lt | 1.9.8 |
datatracker.ietf.org/doc/html/rfc4343
github.com/advisories/GHSA-7774-7vr3-cc8j
github.com/istio/istio/commit/084b417a486dbe9b9024d4812877016a484572b1
github.com/istio/istio/commit/76ed51413ddd2a7fa253a368ab20a9cec5fb1cbe
github.com/istio/istio/commit/90b00bdf891e6c770cb3235c14a9b1fda96cc7c5
github.com/istio/istio/security/advisories/GHSA-7774-7vr3-cc8j
nvd.nist.gov/vuln/detail/CVE-2021-39155
7.5 High
CVSS3
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
NONE
Availability Impact
NONE
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
5 Medium
CVSS2
Access Vector
NETWORK
Access Complexity
LOW
Authentication
NONE
Confidentiality Impact
PARTIAL
Integrity Impact
NONE
Availability Impact
NONE
AV:N/AC:L/Au:N/C:P/I:N/A:N
0.001 Low
EPSS
Percentile
46.8%