CVE-2021-40126
Published: 04 November 2021
Summary
CVE-2021-40126 is a medium-severity Self-generated Error Message Containing Sensitive Information (CWE-210) vulnerability in Cisco Umbrella. Its CVSS base score is 4.3 (Medium).
Operationally, ranked at the 35.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2021-27313
Vulnerability details
A vulnerability in the web-based dashboard of Cisco Umbrella could allow an authenticated, remote attacker to perform an email enumeration attack against the Umbrella infrastructure. This vulnerability is due to an overly descriptive error message on the dashboard that appears…
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when a user attempts to modify their email address when the new address already exists in the system. An attacker could exploit this vulnerability by attempting to modify the user's email address. A successful exploit could allow the attacker to enumerate email addresses of users in the system.
- CWE(s)
Related Threats
No named actor attribution yet. ATT&CK technique mapping in progress for this CVE.
Affected Assets
Mitigating Controls
Likely Mitigating Controls AI
Per-CVE control mapping for this CVE has not run yet; the list below is derived from the weakness types (CWEs) cited in the NVD entry.
Detects error messages that leak sensitive information as evidence of disclosure.
The control directly mitigates generation of error messages containing sensitive authentication details by requiring obscured feedback instead of verbose responses.
Misdirection allows generation of misleading error messages that withhold or falsify sensitive details.
Explicitly requires error messages to avoid including sensitive or exploitable details while still supporting corrective action.
Validation ensures error messages contain only expected, non-sensitive content and blocks leakage via verbose errors.
Fail-safe procedures can be defined to suppress or sanitize error output, reducing generation of messages that contain sensitive information.