CVE-2021-29492
Description
An authorization bypass vulnerability was found in envoyproxy/envoy. An attacker can potentially craft an HTTP request that defines a certain pattern of escaped characters in the URI path (such as %2F, %2f, %5C or %5c), allowing them to bypass the envoy authorization service. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.3 | 8.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | None | None | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Changed | N/A |
| Confidentiality | Low | Low | N/A |
| Integrity Impact | Low | Low | N/A |
| Availability Impact | Low | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
Red Hat CVSS v3 Score Explanation
S:C - Given that this vulnerability is in envoy and the vulnerability is bypassing authorization, the affected component and the impacted are different. For example, a service relying on the authorization provided by envoy will now be potentially vulnerable.
CIA:L - Given that the vulnerable component is in the proxy and may potentially give access to services behind, it is only Low as it's not a complete compromise of the CIA. For example it is very unlikely that a service alone relies upon envoy checking the HTTP headers solely for authorization/authentication.
Acknowledgements
Red Hat would like to thank the Envoy security team for reporting this issue.
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