CVE-2021-39155
Istio Case-Insensitive HTTP Host Header Normalization Vulnerability
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.
INFO
Published Date :
Aug. 24, 2021, 11:15 p.m.
Last Modified :
Feb. 21, 2024, 9:01 p.m.
Source :
[email protected]
Remotely Exploitable :
Yes !
Impact Score :
5.5
Exploitability Score :
2.8
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2021-39155.
| URL | Resource |
|---|---|
| https://datatracker.ietf.org/doc/html/rfc4343 | Third Party Advisory |
| https://github.com/istio/istio/security/advisories/GHSA-7774-7vr3-cc8j | Third Party Advisory |
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
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The following list is the news that have been mention
CVE-2021-39155 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2021-39155 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Modified by [email protected]
May. 14, 2024
Action Type Old Value New Value -
Reanalysis by [email protected]
Feb. 21, 2024
Action Type Old Value New Value Added CWE NIST CWE-863 -
Initial Analysis by [email protected]
Aug. 31, 2021
Action Type Old Value New Value Added CVSS V2 NIST (AV:N/AC:L/Au:N/C:P/I:N/A:N) Added CVSS V3.1 NIST AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Changed Reference Type https://datatracker.ietf.org/doc/html/rfc4343 No Types Assigned https://datatracker.ietf.org/doc/html/rfc4343 Third Party Advisory Changed Reference Type https://github.com/istio/istio/security/advisories/GHSA-7774-7vr3-cc8j No Types Assigned https://github.com/istio/istio/security/advisories/GHSA-7774-7vr3-cc8j Third Party Advisory Added CWE NIST CWE-178 Added CPE Configuration OR *cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* versions up to (excluding) 1.9.8 *cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* versions from (including) 1.10.0 up to (excluding) 1.10.4 *cpe:2.3:a:istio:istio:*:*:*:*:*:*:*:* versions from (including) 1.11.0 up to (excluding) 1.11.1
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2021-39155 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2021-39155
weaknesses.
Exploit Prediction
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.
0.14 }} 0.01%
score
0.49378
percentile