CVE-2021-32777
Published: 24 August 2021
Summary
CVE-2021-32777 is a high-severity Incorrect Behavior Order: Authorization Before Parsing and Canonicalization (CWE-551) vulnerability in Envoyproxy Envoy. Its CVSS base score is 8.6 (High).
Operationally, ranked at the 5.9th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-19541
Vulnerability details
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…
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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.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Periodic review and update of procedures reduces incorrect authorization implementations over time.
Supervision identifies cases where authorization logic incorrectly permits unauthorized actions.
Defining permitted attribute values and auditing modifications reduces the chance of incorrect authorization outcomes due to tampered or missing labels.
The authorization process and usage restrictions help prevent incorrect authorization for remote access types.
Establishing configuration and connection requirements helps ensure correct rather than incorrect authorization for wireless access.
Establishing connection authorization processes for mobile devices helps ensure authorization decisions are correctly implemented rather than incorrect.
Monitoring account use, notifying on changes, and reviewing accounts for compliance corrects incorrect authorization assignments.
Ensures authorization decisions for external system use are correctly implemented and enforced.