Vulnerability Snapshot
CVE-2020-3125 is rated CRITICAL — exploitation is trivial or already observed in the wild and impact is severe. Patch immediately, not on the next maintenance window.
Affected technology: asa_5505_firmware, asa_5505, asa_5510_firmware, asa_5510, asa_5512-x_firmware, plus 5 other product variants.
Executive Summary
A vulnerability in the Kerberos authentication feature of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to impersonate the Kerberos key distribution center (KDC) and bypass authentication on an affected device that is configured to perform Kerberos authentication for VPN or local device access. The vulnerability is due to insufficient identity verification of the KDC when a successful authentication response is received. An attacker could exploit this vulnerability by spoofing the KDC server response to the ASA device. This malicious response would not have been authenticated by the KDC. A successful attack could allow an attacker to bypass Kerberos authentication.
Why It Matters
CVE-2020-3125 is rated CRITICAL severity, requiring immediate attention from security teams.
CVSS Base Score: 9.8/10
Affected Technologies
Vendors: cisco
Products: asa_5505_firmware, asa_5505, asa_5510_firmware, asa_5510, asa_5512-x_firmware, asa_5512-x, asa_5515-x_firmware, asa_5515-x, asa_5520_firmware, asa_5520, asa_5525-x_firmware, asa_5525-x, asa_5540_firmware, asa_5540, asa_5545-x_firmware, asa_5545-x, asa_5550_firmware, asa_5550, asa_5555-x_firmware, asa_5555-x, asa_5580_firmware, asa_5580, asa_5585-x_firmware, asa_5585-x, adaptive_security_appliance_software
🛡️What Defenders Should Check
Use Vulnios to continuously monitor your exposure to CVE-2020-3125 and similar vulnerabilities.
References & Sources
How Vulnios Detects This
Vulnios scans for this vulnerability using Trivy and Grype for SBOM-based CVE matching and Vulnios CVE feed continuous monitoring against your asset inventory. Run a scan against your environment to see whether you are exposed; findings are linked back to the original CVE record so triage starts with the patch path already known.
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Affected Products
Sources
Related Threat Alerts
- Critical Vulnerability: CVE-2021-1142 — cisco — smart_software_manager_satellite
- Critical Vulnerability: CVE-2021-1139 — cisco — smart_software_manager_satellite
- Critical Vulnerability: CVE-2021-1141 — cisco — smart_software_manager_satellite
- Critical Vulnerability: CVE-2021-1300 — cisco — ios_xe_sd-wan, sd-wan_firmware
- Critical Vulnerability: CVE-2021-1301 — cisco — ios_xe_sd-wan, sd-wan_firmware
- Critical Vulnerability: CVE-2021-1138 — cisco — smart_software_manager_satellite
Frequently Asked Questions
What is CVE-2020-3125?
CVE-2020-3125 is a critical-severity vulnerability tracked under the Common Vulnerabilities and Exposures program. A vulnerability in the Kerberos authentication feature of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to impersonate the Kerberos key distribution
Am I affected?
Check whether your environment runs asa_5505_firmware, asa_5505, asa_5510_firmware, asa_5510, asa_5512-x_firmware. If you operate any of those, treat yourself as in scope until you have evidence otherwise. A Vulnios scan will identify the exact assets carrying the affected version.
How urgent is the response?
Critical: do not wait for your normal patch cycle. Verify exposure today, apply the vendor patch immediately, and add detection rules for any post-exploit indicators.
How do I remediate?
Apply the vendor patch listed in the upstream advisory linked under Sources. If the patch is not yet available, follow the vendor-supplied workaround (often a config flag or feature disable) and add detections for the published exploit pattern in your SIEM. Re-scan after the patch lands to confirm the finding clears.
Where can I track exploitation activity?
Watch CISA's Known Exploited Vulnerabilities catalog for CVE-2020-3125. Cross-reference with public exploit databases and your own SIEM/IDS for indicator-of-compromise patterns. Vulnios tracks KEV status automatically and surfaces it on the asset findings view.
How does Vulnios help with this?
Vulnios continuously cross-references your asset inventory against the live CVE feed (NVD, vendor advisories, CISA KEV, and curated OSINT). When a new CVE matches your environment, you get a prioritized finding with the severity, KEV status, exploit-prediction (EPSS), and a direct path to the vendor patch. You can start a free scan from the homepage.
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