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CVE Record

CVE-2026-20303: Cisco Catalyst SD-WAN Security Hardening Release - Input Validation Vulnerabilities

As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco Catalyst SD-WAN engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20303 are related to improper input validation issues that are grouped under the Common Weakness Enumeration (CWE) CWE-20.

CriticalCVSS 9.9Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

Cisco identified multiple improper input-validation flaws in Catalyst SD-WAN Controller and Manager. A network-reachable attacker with low privileges could potentially compromise confidentiality, integrity, and availability without user interaction. Because these systems manage network infrastructure, successful exploitation could have broad operational consequences.

Executive priority

Treat as an urgent network-management risk. Identify affected systems immediately, constrain access, and schedule Cisco-directed upgrades through normal change controls. Prioritize externally reachable or broadly accessible management deployments. There is no supplied evidence of active exploitation, but the 9.9 score and potential infrastructure-wide impact justify accelerated remediation.

Technical view

CVE-2026-20303 groups internally discovered CWE-20 vulnerabilities. CVSS 3.1 is 9.9: network-accessible, low complexity, low privileges, no user interaction, changed scope, and high impact across confidentiality, integrity, and availability. The supplied evidence does not describe the vulnerable interfaces, accepted inputs, or exact exploitation path.

Likely exposure

Exposure is likely where an enumerated Catalyst SD-WAN Controller or Manager version remains deployed and an authenticated attacker can reach the vulnerable service. The extensive affected-version lists span numerous release branches. The bundle provides no CPE mappings, and its default version status is unknown, so unlisted builds require Cisco confirmation.

Exploitation context

The bundle marks this CVE as absent from CISA KEV and provides no evidence of active exploitation, public proof-of-concept code, or weaponization. Cisco describes the issues as internally discovered. Low privileges are required, but the changed-scope and high-impact metrics indicate substantial post-compromise consequences.

Researcher notes

The CVE represents a group of CWE-20 issues rather than one fully documented flaw. The source bundle does not disclose affected endpoints, input formats, root causes, fixed-version boundaries, indicators of compromise, or workaround efficacy. Researchers should avoid inferring exploitability beyond the CVSS vector and consult Cisco's advisory for authoritative release guidance.

Mitigation direction

  • Compare deployed Controller and Manager builds against Cisco's affected-version information.
  • Follow Cisco's advisory for the designated hardening release; fixed versions are not identified in the supplied bundle.
  • Restrict management-plane access to authorized administrative networks and trusted identities.
  • Review low-privilege accounts and remove unnecessary access while remediation is pending.
  • Monitor Cisco guidance for clarifications to affected and fixed release status.

Validation and detection

  • Inventory every Catalyst SD-WAN Controller and Manager instance and record its exact build.
  • Confirm each build's status against the Cisco advisory, including maintenance and engineering releases.
  • Verify vulnerable services are unreachable from untrusted networks and unauthorized user segments.
  • After upgrading, confirm the running build and validate normal management and control-plane operations.
  • Review authentication and administrative logs for anomalous low-privilege activity.
Prepared
Confidence
medium
Sources
3

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

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 · low confidence lookup

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.

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cve · low confidence lookup

CVE-2026-20303 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.9 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Official CVE source material

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.

1CVSS vectors
3Timeline events
2ADP providers
3Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: total

CVSS vector scores

1 official score

We 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.

ScoreVersionSeverityVectorExploitImpactSource
9.9CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H3.16cisco

Vulnerability scoring details

Base CVSS 3.1 score

9.9Critical
CVSS 3.1 vector shape for CVE-2026-20303Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVEADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CiscoCisco Catalyst SD-WAN Controller20.6.4, 20.9.2, 20.3.6, 20.7.2, 20.7.1, 20.5.1, 20.6.2, 19.3.0, 20.6.1, 17.2.4, 18.2.0, 18.4.6, 19.1.0, 19.2.4, 19.2.929, 18.3.8, 18.4.303, 18.3.7, 18.4.1, 19.2.097, 19.2.0, 19.2.099, 18.3.6, 20.4.2, 19.0.0, 20.9.1, 20.3.5, 20.3.1, 18.3.5, 20.6.3, 18.4.3, 18.4.4, 18.3.3, 17.2.8, 20.8.1, 19.2.32, 19.2.2, 17.2.5, 18.4.0, 20.4.1.1, 20.1.3, 20.1.2, 17.2.10, 19.2.098, 20.1.1, 17.2.6, 19.2.1, 18.3.4, 20.4.1, 17.2.9, 19.2.31, 19.0.1a, 18.3.0, 17.2.7, 18.4.5, 20.3.4, 20.3.3, 20.4.1.2, 20.3.2, 18.3.1, 20.1.12, 19.2.3, 20.10.1, 20.6.5, 20.3.7, 20.9.3, 20.11.1, 20.6.3.2, 20.4.2.3, 20.3.5.1, 20.3.4.3, 20.9.3.1, 20.6.4.1, 20.3.3.2, 20.6.5.2, 20.3.7.1, 20.11.1.1, 20.10.1.1, 20.6.1.2, 20.1.3.1, 20.9.2.2, 20.6.5.3, 20.6.3.3, 20.3.7.2, 20.6.5.4, 20.9.2.3, 20.9.4, 20.12.1, 20.3.8, 20.6.6, 20.12.2, 20.13.1, 20.9.5, 20.12.3, 20.6.7, 20.9.5.1, 20.14.1, 20.12.3.1, 20.12.4, 20.15.1, 20.9.6, 20.6.8, 20.16.1, 20.9.5.3, 20.12.4.1, 20.15.2, 20.12.5, 20.9.7, 20.15.3, 20.12.5.1, 20.12.5.2, 20.15.4, 20.9.7.1, 20.18.1, 20.12.6, 20.9.8, 20.15.4.1, 20.18.2, 26.1.1, 20.15.4.2, 20.18.2.1, 20.12.5.3, 20.12.6.1, 20.9.8.2, 20.15.5, 20.18.3, 20.12.7, 20.9.9, 20.18.2.2, 20.12.5.4, 20.12.7.1, 20.15.5.1, 20.15.4.3, 20.12.6.2, 20.15.5.2, 20.15.4.4, 26.1.1.1, 20.9.9.1, 20.18.3.1, 26.1.1.2, 20.15.4.5, 20.15.5.3, 20.12.7.2, 20.9.9.2, 20.15.6unknown
CiscoCisco Catalyst SD-WAN Manager20.1.12, 19.2.1, 18.4.4, 18.4.5, 20.1.1.1, 20.1.1, 19.3.0, 19.2.2, 19.2.099, 18.3.6, 18.3.7, 19.2.0, 18.3.8, 19.0.0, 19.1.0, 18.4.302, 18.4.303, 19.2.097, 19.2.098, 17.2.10, 18.3.6.1, 19.0.1a, 18.2.0, 18.4.3, 18.4.1, 17.2.8, 18.3.3.1, 18.4.0, 18.3.1, 17.2.6, 17.2.9, 18.3.4, 17.2.5, 18.3.1.1, 18.3.5, 18.4.0.1, 18.3.3, 17.2.7, 17.2.4, 18.3.0, 19.2.3, 18.4.501_ES, 20.3.1, 20.1.2, 19.2.929, 19.2.31, 20.3.2, 19.2.32, 20.3.2_925, 20.3.2.1, 20.3.2.1_927, 18.4.6, 20.1.2_937, 20.4.1, 20.3.2_928, 20.3.2_929, 20.4.1.0.1, 20.3.2.1_930, 19.2.4, 20.5.0.1.1, 20.4.1.1, 20.3.3, 19.2.4.0.1, 20.3.2_937, 20.3.3.1, 20.5.1, 20.1.3, 20.3.3.0.4, 20.3.3.1.2, 20.3.3.1.1, 20.4.1.2, 20.3.3.0.2, 20.4.1.1.5, 20.4.1.0.01, 20.4.1.0.02, 20.3.3.1.7, 20.3.3.1.5, 20.5.1.0.1, 20.3.3.1.10, 20.3.3.0.8, 20.4.2, 20.4.2.0.1, 20.3.4, 20.3.3.0.14, 19.2.4.0.8, 19.2.4.0.9, 20.3.4.0.1, 20.3.2.0.5, 20.6.1, 20.5.1.0.2, 20.3.3.0.17, 20.6.1.1, 20.6.0.18.3, 20.3.2.0.6, 20.6.0.18.4, 20.4.2.0.2, 20.3.3.0.16, 20.3.4.0.5, 20.6.1.0.1, 20.3.4.0.6, 20.6.2, 20.7.1EFT2, 20.3.4.0.9, 20.3.4.0.11, 20.4.2.0.4, 20.3.3.0.18, 20.7.1, 20.6.2.1, 20.3.4.1, 20.5.1.1, 20.4.2.1, 20.4.2.1.1, 20.3.4.1.1, 20.3.813, 20.3.4.0.19, 20.4.2.2.1, 20.5.1.2, 20.3.4.2, 20.3.814, 20.4.2.2, 20.6.2.2, 20.3.4.2.1, 20.7.1.1, 20.3.4.1.2, 20.6.2.2.2, 20.3.4.0.20, 20.6.2.2.3, 20.4.2.2.2, 20.3.5, 20.6.2.0.4, 20.4.2.2.3, 20.3.4.0.24, 20.6.2.2.7, 20.6.3, 20.3.4.2.2, 20.4.2.2.4, 20.7.1.0.2, 20.8.1, 20.3.5.0.8, 20.3.5.0.9, 20.4.2.2.8, 20.3.5.0.7, 20.6.3.0.7, 20.6.3.0.5, 20.6.3.0.10, 20.6.3.0.2, 20.7.2, 20.9.1EFT2, 20.6.3.0.11, 20.6.3.1, 20.6.3.0.14, 20.6.4, 20.9.1, 20.6.3.0.19, 20.6.3.0.18, 20.3.6, 20.9.1.1, 20.6.3.0.23, 20.6.4.0.4, 20.6.3.0.25, 20.6.5, 20.6.3.0.27, 20.9.2, 20.9.2.1, 20.6.3.0.29, 20.6.3.0.31, 20.6.3.0.32, 20.10.1, 20.6.3.0.33, 20.9.2.0.01, 20.9.1_LI_Images, 20.10.1_LI_Images, 20.9.2_LI_Images, 20.3.7, 20.9.3, 20.6.5.1, 20.11.1, 20.11.1_LI_Images, 20.9.3_LI_ Images, 20.6.3.1.1, 20.9.3.0.2, 20.6.5.1.2, 20.9.3.0.3, 20.4.2.3, 20.6.3.2, 20.6.4.1, 20.6.3.0.38, 20.6.3.0.39, 20.3.5.1, 20.3.4.3, 20.9.3.1, 20.3.3.2, 20.6.5.2, 20.3.7.1, 20.10.1.1, 20.6.5.2.1, 20.3.4.0.25, 20.6.2.2.4, 20.6.1.2, 20.11.1.1, 20.9.3.0.5, 20.3.4.0.26, 20.6.5.1.3, 20.6.3.0.40, 20.1.3.1, 20.9.2.2, 20.6.5.2.3, 20.6.5.1.4, 20.6.5.3, 20.6.3.0.41, 20.9.3.0.7, 20.6.5.1.5, 20.9.3.0.4, 20.6.4.0.19, 20.6.5.1.6, 20.9.3.0.8, 20.6.3.3, 20.3.7.2, 20.6.5.4, 20.6.5.1.7, 20.9.3.0.12, 20.6.4.2, 20.6.5.5, 20.9.3.2, 20.11.1.2, 20.6.3.4, 20.10.1.2, 20.6.5.1.9, 20.9.3.0.16, 20.6.3.0.45, 20.6.5.1.10, 20.9.3.0.17, 20.6.5.2.4, 20.6.4.0.21, 20.9.3.0.18, 20.6.3.0.46, 20.6.3.0.47, 20.9.2.3, 20.9.3.2_LI_Images, 20.9.3.0.21, 20.9.3.0.20, 20.9.4_LI_Images, 20.9.4, 20.6.5.1.11, 20.12.1, 20.12.1_LI_Images, 20.6.5.1.13, 20.9.3.0.23, 20.6.5.2.8, 20.9.4.1, 20.9.4.1_LI_Images, 20.9.3.0.25, 20.9.3.0.24, 20.6.5.1.14, 20.3.8, 20.6.6, 20.9.3.0.26, 20.6.3.0.51, 20.9.3.0.29, 20.12.2, 20.12.2_LI_Images, 20.6.6.0.1, 20.13.1_LI_Images, 20.9.4.0.4, 20.13.1, 20.9.4.1.1, 20.9.5, 20.9.5_LI_Images, 20.12.3_LI_Images, 20.12.3, 20.9.4.1.3, 20.6.7, 20.9.5.1, 20.9.5.1_LI_Images, 20.9.4.1.6, 20.14.1, 20.14.1_LI_Images, 20.9.5.2, 20.9.5.2.1, 20.9.5.2_LI_Images, 20.12.3.1, 20.12.4, 20.15.1_LI_Images, 20.15.1, 20.9.5.1.4, 20.9.5.2.7, 20.9.5.2.13, 20.9.6, 20.9.6_LI_Images, 20.9.5.2.14, 20.6.8, 20.12.4.0.03, 20.16.1, 20.16.1_LI_Images, 20.12.4_LI_Images, 20.9.5.2.16, 20.12.4.0.4, 20.12.401, 20.9.5.3, 20.9.5.3_LI_Images, 20.12.4.1_LI_Images, 20.12.4.1, 20.9.5.2.21, 20.9.6.0.3, 20.12.4.0.6, 20.15.2_LI_Images, 20.15.2, 20.12.4_Monthly_ES5, 20.12.5, 20.12.5_LI_Images, 20.9.7_LI _Images, 20.9.7, 20.15.3, 20.15.3_ LI _Images, 20.12.501, 20.12.5.1_LI_Images, 20.12.5.1, 20.12.5.2_LI_Images, 20.12.5.2, 20.15.3.1, 20.15.4_LI_Images, 20.15.4, 20.9.7.1_LI _Images, 20.9.7.1, 20.18.1, 20.18.1_LI_Images, 20.12.6_LI_Images, 20.12.6, 20.12.5.1.01, 26.0.1, 20.9.8, 20.9.8_LI_Images, 20.18.2, 20.15.4.1_LI_Images, 20.15.4.1, 20.18.2_LI_Images, 26.1.1, 26.1.1_LI_Images, 20.18.2.1_LI_Images, 20.18.2.1, 20.15.4.2_LI_Images, 20.15.4.2, 20.12.6.1, 20.12.6.1_LI_Images, 20.12.5.3, 20.12.5.3_LI_Images, 20.9.8.2_LI_Images, 20.9.8.2, 20.18.3, 20.18.3_LI_Images, 20.15.5, 20.15.5_LI_Images, 20.12.7, 20.12.7_LI_Images, 20.9.9, 20.9.9_LI_Images, 20.18.2.2, 20.18.2.2_LI_Images, 20.12.5.4, 20.12.5.4_LI_ Images, 20.12.7.1_LI_Images, 20.12.6.2_LI_Images, 20.12.7.1, 20.15.5.1, 20.15.4.3, 20.15.4.3_LI_Images, 20.15.5.1_LI_Images, 20.12.6.2, 20.15.5.2, 20.15.5.2_LI_Images, 26.1.1.1_LI_Images, 20.15.4.4, 20.15.4.4_LI_Images, 26.1.1.1, 20.9.9.1_LI_Images, 20.9.9.1, 20.18.3.1_LI_Images, 20.18.3.1, 26.1.1.2, 26.1.1.2_LI_Images, 20.15.4.5, 20.15.4.5_LI_Images, 20.15.5.3, 20.15.5.3_LI_Images, 20.12.7.2_LI_Images, 20.12.7.2, 20.9.9.2, 20.9.9.2_LI_Images, 20.15.6, 20.15.6_LI_Imagesunknown
Weakness

CWE details

CWE-20

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-20 · source CWE mapping

Improper Input Validation

Improper Input Validation represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs