CVE-2020-3248: Cisco UCS Director REST API authentication bypass and path traversal

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 18 September 2026. Confidence: medium.

critical priorityCVSS 9.8 with network reachability, no authentication and no user interaction, plus very high EPSS, makes this a top remediation priority despite the thin advisory detail.

What it is

Multiple flaws in the REST API of Cisco UCS Director and UCS Director Express for Big Data allow a remote, unauthenticated attacker to bypass authentication or perform directory traversal. The advisory groups several issues together and does not detail each one, so the exact per-flaw mechanics are not fully described. With a CVSS base score of 9.8, the exposure is severe for any internet- or network-reachable management interface.

Impact

An attacker can reach protected REST API functionality without valid credentials and read or write files outside the intended directory, potentially leading to full compromise of the affected appliance.

Attack surface

Reachable over the network via the REST API (AV:N, AC:L, PR:N, UI:N); no authentication or user interaction is required. The advisory does not specify which endpoints are affected.

Exploitation

Not listed in CISA KEV and no ransomware usage is documented, but EPSS is very high (0.744, ~99.5th percentile), indicating elevated likelihood of attempted exploitation. References are vendor and third-party advisories only; no public exploit code is cited in the record.

What to do

• Apply the Cisco security advisory fixes for UCS Director and UCS Director Express for Big Data as the first action.
• Restrict network access to the REST API management interface using firewalls, ACLs or management VLANs; do not expose it to the internet.
• Require strong authentication and, where supported, place the interface behind a reverse proxy or VPN with additional authentication.
• Monitor vendor advisory updates for revised fixed versions, since the record does not list affected or fixed releases.
• Audit file system and API logs for unexpected traversal patterns or unauthenticated API calls.

Detection

• Alert on REST API requests containing path traversal sequences such as ../ or encoded variants in URLs or parameters.
• Baseline and monitor API calls from unexpected source IPs, especially unauthenticated requests to privileged endpoints.
• Review web server and application logs for anomalous file access or reads outside expected directories.
• Track authentication failures and unusual successful API sessions on UCS Director hosts.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.