Infinite open connection causes OctoRPKI to hang forever

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2021-3909: 1.57% estimated exploitation activity in the next 30 days; percentile 75.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

OctoRPKI (github.com/cloudflare/cfrpki/cmd/octorpki) does not limit the length of a connection, allowing for a slowloris DOS attack to take place which makes OctoRPKI wait forever. Specifically, the repository that OctoRPKI sends HTTP requests to will keep the connection open for a day before a response is returned, but does keep drip feeding new bytes to keep the connection alive. Patches For more information If you have any questions or comments about this advisory email us at security@cloudflare.com

Published by the source

10 Nov 2021, 20:15 UTC

Last modified by the source

2 Oct 2023, 15:56 UTC

Source last checked

26 Oct 2026, 14:59 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8cvr-4rrf-f244

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# Patch Next advisory brief: CVE-2021-3909

Advisory: Infinite open connection causes OctoRPKI to hang forever
IDs: CVE-2021-3909, GHSA-8cvr-4rrf-f244
Record: https://patchnext.com/advisories/cve-2021-3909 (revision 1, source checked 26 Oct 2026, 14:59 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 4.4)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: github.com/cloudflare/cfrpki 1.4.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/cloudflare/cfrpki: affected < 1.4.0; fixed in 1.4.0

## Suggested inspection (read-only)
- Go github.com/cloudflare/cfrpki: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/cloudflare/cfrpki.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8cvr-4rrf-f244 (GitHub-reviewed advisory GHSA-8cvr-4rrf-f244 lists affected ranges: Go github.com/cloudflare/cfrpki >=0 <1.4.0)

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