CVE-2021-32777
This may allow specifically crafted requests to bypass authorization.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (3.33%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 3.1
- 8.3 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
- EPSS
- 3.33% probability · 88th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-551, CWE-863
- Affected
- envoyproxy/envoy
- Source
- security-advisories@github.com
References
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-6g4j-5vrw-2m8hThird Party Advisory
- https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyRelease Notes, Vendor Advisory
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-6g4j-5vrw-2m8hThird Party Advisory
- https://www.envoyproxy.io/docs/envoy/v1.19.0/version_history/version_historyRelease Notes, Vendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.