CVE-2021-32781
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-120 · CWE-416
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 after Envoy sends a locally generated response it must stop further processing of request or response data. However when local response is generated due the internal buffer overflow while request or response is processed by the filter chain the operation may not be stopped completely and result in accessing a freed memory block. A specifically constructed request delivered by an untrusted downstream or upstream peer in the presence of extensions that modify and increase the size of request or response bodies resulting in a Denial of Service when using extensions that modify and increase the size of request or response bodies, such as decompressor filter. Envoy versions 1.19.1, 1.18.4, 1.17.4, 1.16.5 contain fixes to address incomplete termination of request processing after locally generated response. As a workaround disable Envoy's decompressor, json-transcoder or grpc-web extensions or proprietary extensions that modify and increase the size of request or response bodies, if feasible.
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-2021-32781?format=txt
- CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-32781?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.ioVendor 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:U/C:N/I:N/A:H
- Published
- 2021-08-24
- Last Modified
- 2026-06-17
- NVD status
- Modified
Frequently asked questions
What is CVE-2021-32781?
Is CVE-2021-32781 actively exploited?
What is the CVSS score for CVE-2021-32781?
Running Envoy? Hear about its next vulnerability
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.