Cloudflare Universal SSL automatically managed CAA RRset supersedes customer-configured CAA records
Summary
| CVE | CVE-2026-14440 |
|---|---|
| State | PUBLISHED |
| Assigner | cloudflare |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-01 23:16:52 UTC |
| Updated | 2026-07-02 20:17:01 UTC |
| Description | Description: To issue and renew TLS certificates on behalf of customers, Cloudflare's Universal SSL feature automatically manages the CAA RRset for the customer's zone. This auto-managed RRset is permissive by design (e.g. 'issue "letsencrypt.org"' without parameters). On Universal SSL zones, Cloudflare's authoritative DNS serves this auto-managed RRset at query time, superseding any customer-configured CAA records on the zone. When a customer publishes a stricter CAA record using the RFC 8657 accounturi or validationmethods parameters, the Certificate Authority does not observe those parameters when evaluating the served RRset under RFC 8659. As a result, the RFC 8657 account-binding and validation-method-binding protections are not enforced end-to-end on Universal SSL zones. Successful exploitation could result in issuance of a browser-trusted TLS certificate to an attacker, enabling MITM against the affected domain. Exploitation is non-trivial in practice: an attacker would need to hold an ACME account at one of the Certificate Authorities in the served CAA RRset and to simultaneously satisfy domain control validation across the multiple geographically distinct Network Perspectives the CA relies on for Multi-Perspective Issuance Corroboration. Cloudflare prefixes are anycast-announced from hundreds of locations globally, raising the bar against single-vantage-point BGP hijacks. Any resulting misissuance of a browser-trusted certificate is subject to Certificate Transparency logging required by major browsers, and would be visible to CT monitoring. Mitigation: Customers requiring strict RFC 8657 enforcement need to disable Universal SSL on the affected zone. Universal SSL's automatic CAA management and customer-set RFC 8657 accounturi and validationmethods enforcement are mutually exclusive by the nature of the issue, so there is no in-product workaround that preserves both. Certificate Transparency monitoring is recommended for all customers as a general detection control. Credits: David Osipov (ORCID: https://orcid.org/0009-0005-2713-9242), independent researcher |
Risk And Classification
Primary CVSS: v4.0 7.6 HIGH from [email protected]
CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS: 0.001350000 probability, percentile 0.033320000 (date 2026-07-05)
Problem Types: CWE-693 | CWE-693 CWE-693 Protection Mechanism Failure
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | [email protected] | Secondary | 7.6 | HIGH | CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 7.6 | HIGH | CVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N |
| 3.1 | ADP | DECLARED | 6.8 | MEDIUM | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 6.8 | MEDIUM | CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N |
CVSS v4.0 Breakdown
Attack Vector
AdjacentAttack Complexity
HighAttack Requirements
PresentPrivileges Required
NoneUser Interaction
NoneConfidentiality
HighIntegrity
HighAvailability
NoneSub Conf.
NoneSub Integrity
NoneSub Availability
NoneCVSS:4.0/AV:A/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CVSS v3.1 Breakdown
Attack Vector
AdjacentAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
NoneCVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Cloudflare | Universal SSL | affected current custom | Cloud Service |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| david-osipov.vision/en/blog/cybersecurity/cloudflare-ssl-mitm-flaw-2026 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | david-osipov.vision | |
| developers.cloudflare.com/ssl/edge-certificates/universal-ssl/limitations | [email protected] | developers.cloudflare.com | |
| zenodo.org/records/18330221 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | zenodo.org | |
| www.rfc-editor.org/rfc/rfc8659 | [email protected] | www.rfc-editor.org | |
| community.cloudflare.com/t/critical-security-gap-cloudflare-must-fully-support-rfc-865... | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | community.cloudflare.com | |
| community.cloudflare.com/t/universal-ssl-exposes-domains-to-bgp-leaks-re-venezuela-ana... | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | community.cloudflare.com | |
| www.rfc-editor.org/rfc/rfc8657 | [email protected] | www.rfc-editor.org | |
| developers.cloudflare.com/ssl/edge-certificates/caa-records | [email protected] | developers.cloudflare.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: David Osipov (ORCID: https://orcid.org/0009-0005-2713-9242), independent researcher (en)
Additional Advisory Data
Solutions
CNA: Customers requiring strict RFC 8657 enforcement need to disable Universal SSL on the affected zone. Universal SSL's automatic CAA management and customer-set RFC 8657 accounturi and validationmethods enforcement are mutually exclusive by the nature of the issue, so there is no in-product workaround that preserves both. Certificate Transparency monitoring is recommended for all customers as a general detection control.
There are currently no legacy QID mappings associated with this CVE.