Security readout for executives and security teams
Plain-English summary
This flaw lets a highly privileged local administrator on an affected Cisco IOS or IOS XE device abuse the Tcl interpreter to run code as root. It is serious if privileged device access is shared, compromised, or weakly controlled, but it is not a remote unauthenticated vulnerability.
Executive priority
Treat this as a controlled-access but high-impact network device risk. It should not outrank internet-facing unauthenticated flaws, but it deserves prompt remediation where administrator access is broad, poorly audited, or exposed through jump hosts.
Technical view
CVE-2020-3204 is an input-validation flaw in the Cisco IOS and IOS XE Tcl interpreter. Cisco describes arbitrary code execution on the underlying OS with root privileges after malicious Tcl code is loaded by an authenticated local attacker with privileged EXEC credentials. CVSS is 6.7 with high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to affected Cisco IOS and IOS XE devices where an attacker can obtain privileged EXEC access. The supplied affected entry names Cisco IOS 12.2(53)SE1, but the complete affected and fixed version matrix should be confirmed in Cisco’s advisory.
Exploitation context
The provided sources do not show CISA KEV listing or confirmed active exploitation. Exploitation requires privileged local access, so the main risk is compromised administrators, shared admin accounts, weak AAA controls, or insider misuse on affected network devices.
Researcher notes
Key constraints are AV:L and PR:H, with no user interaction and unchanged scope. The weakness is CWE-20 insufficient input validation. The impact is severe after access is obtained: root-level code execution or memory corruption on the underlying operating system.
Mitigation direction
- Review Cisco’s advisory for affected releases and fixed software guidance.
- Prioritize upgrades for devices where many users hold privileged EXEC access.
- Restrict privileged EXEC access to named, trusted administrators only.
- Review AAA, MFA, and logging controls for network device administration.
- Investigate unexpected Tcl interpreter use on affected Cisco devices.
Validation and detection
- Inventory Cisco IOS and IOS XE devices and record software versions.
- Compare device versions against Cisco’s advisory for CVE-2020-3204.
- Confirm who has privileged EXEC access on each affected device.
- Review administrative logs for unusual Tcl activity or memory corruption events.
- Verify remediation status after any software upgrade or configuration change.
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-20: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2020-3204 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
- Medium
- CVSS
- 6.7 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:L/AC:L/PR:H/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:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H0.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
6.7MediumVector: CVSS:3.0/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- 20200603 Cisco IOS and IOS XE Software Tcl Arbitrary Code Execution 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 Input Validation
Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.