CVE-2021-3978 — cfrpki
MEDIUMCVE-2021-3978 is a medium-severity (CVSS 5.5) Improper Privilege Management vulnerability in github.com/cloudflare/cfrpki. A fix is available for github.com/cloudflare/cfrpki — see the affected versions and patch details below.
Improper Preservation of Permissions in github.com/cloudflare/cfrpki/cmd/octorpki
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2021-3978.
EPSS Exploitation Probability
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
github.com/cloudflare/cfrpkiReal-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
Impact
When copying files with rsync, octorpki uses the "-a" flag 0, which forces rsync to copy binaries with the suid bit set as root. Since the provided service definition defaults to root (https://github.com/cloudflare/cfrpki/blob/master/package/octorpki.service) this could allow for a vector, when combined with another vulnerability that causes octorpki to process a malicious TAL file, for a local privilege escalation.
For more information
If you have any questions or comments about this advisory email us at [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/cloudflare/cfrpki | all versions | 1.4.2go get github.com/cloudflare/cfrpki@v1.4.2 |
Affected Products
octorpkicloudflareDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/cloudflare/cfrpki, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/cloudflare/cfrpki to 1.4.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-3978 is resolved across your whole dependency graph.
Workarounds
Close the privilege gap rather than the entry point: audit which accounts, roles and service identities can reach the affected operation, drop the component to the least privilege it actually needs, and review file and directory permissions created by earlier installs — a default left in place is what makes this reachable.
Frequently Asked Questions
Is CVE-2021-3978 in your dependencies?
Find it across Go, including transitive dependencies.