Security readout for executives and security teams
Plain-English summary
CVE-2020-3516 is a Cisco IOS XE Web UI flaw that can let a logged-in remote attacker crash the device web server. It affects availability of the management interface, not confidentiality or integrity. Recovery may require manually disabling and re-enabling the web server.
Executive priority
Treat this as a moderate operational risk for Cisco IOS XE management availability. Prioritize internet- or broadly reachable management interfaces, then handle through normal network infrastructure patch and hardening cycles.
Technical view
Cisco describes improper input validation during Web UI authentication in IOS XE Software. An authenticated remote attacker using unexpected characters during valid authentication could crash the device web server. The CVSS 3.0 score is 4.3, with network access, low complexity, low privileges, no user interaction, and low availability impact.
Likely exposure
Exposure is most likely where Cisco IOS XE devices have the Web UI enabled and reachable by authenticated administrators or compromised administrative accounts. The provided sources do not identify specific affected releases, CPEs, or deployment counts.
Exploitation context
The source bundle does not show CISA KEV listing or other evidence of active exploitation. Exploitation requires authenticated access, limiting opportunistic risk, but a compromised or malicious low-privilege account could disrupt web-based device administration.
Researcher notes
Evidence supports CWE-20 improper input validation in Web UI authentication, authenticated remote reachability, and availability-only impact. The bundle does not provide affected version ranges, proof of exploitation, or detailed remediation beyond the Cisco advisory reference.
Mitigation direction
- Review Cisco’s advisory for affected IOS XE releases and fixed software guidance.
- Restrict Web UI access to trusted administrative networks and users.
- Disable the Web UI where it is not operationally required, after confirming vendor guidance.
- Strengthen administrative account controls, including least privilege and credential hygiene.
- Prepare recovery procedures for manually restarting the device web server.
Validation and detection
- Inventory Cisco IOS XE devices and record release, role, and Web UI exposure.
- Confirm whether administrative web access is reachable from untrusted networks.
- Compare deployed releases against Cisco’s advisory and any vendor software guidance.
- Review administrative account scope for unnecessary Web UI access.
- Check operational runbooks for web server recovery steps.
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
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CWE-20: Exact CWE lookup
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Open ATT&CK lookupCVE-2020-3516 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
- 4.3 (3.0)
- Known Exploited
- No
- Published
Vector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
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:L/PR:L/UI:N/S:U/C:N/I:N/A:L2.81.4Primary CVE scoreVulnerability scoring details
Base CVSS 3.0 score
4.3MediumVector: CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Source materials
- CVE List V5 sourceCVE List V5
- 20200924 Cisco IOS XE Software Web UI Improper Input Validation 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.