What is CVE-2021-43669?

CVE-2021-43669 is a high-severity vulnerability in Linuxfoundation Fabric, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 7.5/10. Published 2021-11-18.

How severe is CVE-2021-43669?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Linuxfoundation Fabric

CVE-2021-43669

A vulnerability has been detected in HyperLedger Fabric v1.4.0, v2.0.0, v2.0.1, v2.3.0. It can easily break down as many orderers as the attacker wants. This bug can be leveraged by constructing a message whose header is invalid to the interface Order. This bug has been admitted and fixed by the developers of Fabric.

Vulnerability class: HTTP Request Smuggling

Published 2021-11-18 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.011 (65.0th percentile), scored 2026-09-29.

Low probability of exploitation in the next 30 days, but still tracked. 65th percentile — 65.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.011 · newest: 0.011 · change: +0.000

Affected products

Linuxfoundation Fabric — versions 1.4.0, 2.0.0, 2.0.1

Weakness classification (CWE)

CWE-444 — Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling)

References

jira.hyperledger.org/browse/FAB-18528 (Vendor Advisory)
github.com/hyperledger/fabric/pull/2828 (Patch, Third Party Advisory)

Frequently asked questions

What is CVE-2021-43669?: CVE-2021-43669 is a high-severity vulnerability in Linuxfoundation Fabric, classified under Inconsistent Interpretation of HTTP Requests (HTTP Request/Response Smuggling). CVSS score: 7.5/10. Published 2021-11-18.
How severe is CVE-2021-43669?: High severity. CVSS v3 base score is 7.5 out of 10.