CVE-2021-32777
No exploitation reported by the sources we read.
- Published2021-08-24
- Fixed in1.19.1 · 1.18.4 · 1.17.4 · 1.16.5
- WeaknessCWE-551 · CWE-863
Am I affected?
Debian, Ubuntu or Red Hat sometimes backport a fix without changing the upstream version number: such a version reads « to verify », never « affected ».With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.
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.
Timeline
dates in UTC- 2021-08-2421:15CVE publishedNVD
Observed activity
isMalicious corpus · updated 2026-10-23 21:37 UTCBlock these indicators
- Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-32777?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-32777?format=csv
- TAXII collection of exploited CVEs
- The EDL and CSV take an API key on the Pro plan.
Versions per branch
OSV · NVD| Branch | Affected | Fixed in | Source |
|---|---|---|---|
| 1.19 | ≥ 1.19.0, < 1.19.1 | 1.19.1 | OSV |
| 1.18 | ≥ 1.18.0, < 1.18.4 | 1.18.4 | NVD · OSV |
| 1.17 | ≥ 1.17.0, < 1.17.4 | 1.17.4 | NVD · OSV |
| 1.16 | ≥ 1.16.0, < 1.16.5 | 1.16.5 | NVD · OSV |
| 1.19 | = 1.19.0 | no fix published | NVD |
as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.
Fix
- Update Envoy to 1.19.1 · 1.18.4 · 1.17.4 · 1.16.5
Advisories and patches
- www.envoyproxy.ioRelease Notes · Vendor Advisory
Detection
- Nuclei template
- none so far ProjectDiscovery
- Exploit-DB
- no entry Exploit-DB
- Proof-of-concept repositories
- none listed PoC-in-GitHub
Sources
Technical details
- CVSS v3 Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:L
- Published
- 2021-08-24
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-32777?
Is CVE-2021-32777 actively exploited?
What is the CVSS score for CVE-2021-32777?
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Surveillance reads the versions in your stack — a domain, a lockfile or a list — checks each CVE against the ranges its sources publish, and alerts you when one you run is exploited or enters CISA KEV. A version it cannot read stays « version not verified ».
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Related vulnerabilities
Same product first, then the same vendor advisory and the same publication week.