CVE-2021-32777
Incorrect concatenation of multiple value request headers in ext-authz extension
Description
Envoy is an open source L7 proxy and communication bus designed for large modern service oriented architectures. In affected versions when ext-authz extension is sending request headers to the external authorization service it must merge multiple value headers according to the HTTP spec. However, only the last header value is sent. This may allow specifically crafted requests to bypass authorization. Attackers may be able to escalate privileges when using ext-authz extension or back end service that uses multiple value headers for authorization. A specifically constructed request may be delivered by an untrusted downstream peer in the presence of ext-authz extension. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to the ext-authz extension to correctly merge multiple request header values, when sending request for authorization.
How to fix CVE-2021-32777
To remediate CVE-2021-32777, upgrade the affected package to a fixed version below.
- —upgrade to 1.16.5 or later
Is CVE-2021-32777 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- >= 1.16.0, < 1.16.5, >= 1.17.0, < 1.17.4, >= 1.18.0, < 1.18.4, >= 1.19.0, < 1.19.1
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH8.3 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L |