Security readout for executives and security teams
Plain-English summary
This flaw affects Cisco ASA devices that use Kerberos for VPN or local device access. An unauthenticated remote attacker could spoof a trusted Kerberos server response and bypass authentication. The business risk is unauthorized access to security infrastructure or VPN entry points, but the source rates attack complexity as high.
Executive priority
Treat as high priority for ASA systems protecting VPN or administrative access. It can undermine authentication on security boundary devices, but urgency should be scoped to Kerberos-enabled ASA deployments and current Cisco remediation guidance.
Technical view
CVE-2020-3125 is a CWE-287 authentication flaw in Cisco ASA Software Kerberos handling. ASA insufficiently verifies the Kerberos KDC identity when receiving a successful authentication response. A spoofed KDC response could let an unauthenticated remote attacker bypass Kerberos authentication on configured VPN or local access paths.
Likely exposure
Exposure is limited to Cisco ASA Software deployments configured to perform Kerberos authentication for VPN access or local device access. ASA devices not using Kerberos for those functions are not indicated as affected by the supplied sources.
Exploitation context
The source bundle does not identify public exploitation, and KEV status is false. Exploitation is described as remote and unauthenticated, but with high attack complexity because the attacker must spoof a successful KDC response accepted by ASA.
Researcher notes
The key exposure condition is ASA Kerberos authentication for VPN or local access. The provided evidence does not include affected version ranges, fixed versions, workaround details, or exploitation sightings, so validation should start with configuration inventory and the Cisco advisory.
Mitigation direction
- Identify ASA devices using Kerberos authentication for VPN or local access.
- Review Cisco advisory guidance for affected and fixed ASA Software releases.
- Prioritize remediation on internet-facing VPN and administrative access paths.
- Use alternate authentication controls only if Cisco guidance supports them.
- Monitor vendor advisories for any updated remediation details.
Validation and detection
- Inventory Cisco ASA Software versions across perimeter and VPN environments.
- Confirm whether Kerberos is enabled for VPN or local device authentication.
- Compare each device against Cisco advisory affected-release guidance.
- Verify remediation status after any ASA Software upgrade or configuration change.
- Review authentication logs for unusual successful access during suspected exposure windows.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-287: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-3125 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 8.1 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H2.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
8.1HighVector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200506 Cisco Adaptive Security Appliance Software Kerberos Authentication Bypass VulnerabilityCVE reference · vendor-advisory, x_refsource_CISCO
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Authentication
Improper Authentication represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.