How severe is CVE-2021-43669?

CVE-2021-43669 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-43669?

CVE-2021-43669 affects the following packages: github.com/hyperledger/fabric (Go). Ecosystems affected: Go.

How do I fix CVE-2021-43669?

Update github.com/hyperledger/fabric to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43669 is resolved across your whole dependency graph.

How do I detect CVE-2021-43669 in my Go dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/hyperledger/fabric, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-43669 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-43669 actively exploited in the wild?

No public exploit code has been indexed for CVE-2021-43669 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2021-43669?

CVE-2021-43669 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 67th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-43669?

CVE-2021-43669 is classified as CWE-444 (CWE-444). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-43669 published, and has it been updated?

CVE-2021-43669 was published on November 18, 2021 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐹

🐹 Go

Not in CISA KEV

HIGH severity

CVE-2021-43669 — fabric

HIGHFix: hyperledger/fabric#2828

CVE-2021-43669 is a high-severity (CVSS 7.5) CWE-444 vulnerability in github.com/hyperledger/fabric. A fix is available for github.com/hyperledger/fabric — see the affected versions and patch details below.

HTTP Request Smuggling in github.com/hyperledger/fabric

Also known asGHSA-j96p-r523-8r3w

Published

Nov 18, 2021

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs67th percentile — riskier than 67% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

🐹github.com/hyperledger/fabric

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

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.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐹Go	`github.com/hyperledger/fabric`	all versions	2.4.0`go get github.com/hyperledger/fabric@v2.4.0`

Affected Products

1 product · 4 configurations

Application

fabriclinuxfoundation

4 versions

1.4.02.0.02.0.12.3.0

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/hyperledger/fabric, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/hyperledger/fabric to 2.4.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43669 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2021-43669 in your dependencies?

Find it across Go, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

7.5/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Raw vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE Classification

CWE-444CWE-444

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

Timeline

Disclosed

Nov 18, 2021

Last updated

Oct 20, 2026

Identifiers

CVE-2021-43669

GHSA-j96p-r523-8r3w

References

Advisoryjira.hyperledger.org · FAB 18528 Advisorynvd.nist.gov · CVE 2021 43669 Fixgithub.com Webgithub.com · v2.4.0 beta Packagegithub.com · fabric

Related vulnerabilities

Also affects fabric

This CVE is high severity; 5 of 6 other CVEs affecting fabric are rated as high or higher (top: high).

CVE-2024-45244CVE-2023-46132CVE-2022-36023CVE-2022-35253CVE-2022-31121CVE-2021-43667

Same weakness: CWE-444

This CVE is high severity; 1 of 2 other CVEs with CWE-444 is rated as high or higher (top: critical).

CVE-2026-55458CVE-2026-118264Browse all CWE-444

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026

CVE-2021-43669 — fabric

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-43669 in your dependencies?