CYBERSECURITY | VENDOR & THIRD-PARTY RISK
Written by: Devensa AI

Figure: The share of breaches involving a third party rose from 15% to 30% to 48% across three editions of the Verizon DBIR. Sources: Verizon 2025 DBIR Executive Summary; Verizon 2026 DBIR.111
Third-party security risk is the exposure an organization inherits through its vendors’ systems, credentials, and integrations. Vendor questionnaires record what a supplier says about its controls on one day; attackers exploit what those controls look like on every other day. Verizon’s 2026 DBIR found a third party involved in 48% of breaches, up 60% in a year.1
A Questionnaire Is a Snapshot of a Promise
The standard security questionnaire, whether a SIG, a CAIQ, or a custom spreadsheet, asks a vendor to attest to its controls. That is useful for screening, but it is self-reported, dated the moment it is returned, and it describes intent more reliably than configuration. SecurityScorecard’s 2026 research found that 67% of organizations still rely on point-in-time audits to assess third-party threats.2
Third-party security risk reaches beyond the vendor’s own network. It includes the credentials you issued the vendor, the integrations linking their platform to yours, the software they ship, and the suppliers they depend on. It is often treated as a procurement checkpoint, a gate passed once. It functions better as a relationship monitored for as long as the access exists.
Five Things That Slip Past the Form
1. Credential and configuration hygiene
Verizon’s analysts cite missing multi-factor authentication, improper credential rotation, and absent least-privilege enforcement as core problems in third-party breaches.3 A questionnaire can ask whether a vendor requires MFA. It rarely shows whether MFA is enforced on the specific support login that touches your data.
2. Integrations and OAuth connections
The 2026 DBIR describes attackers exploiting vendors, SaaS platforms, and OAuth integrations.4 Connected apps often hold broad, long-lived permissions granted by one administrator years ago. They appear in no questionnaire because the risk sits in your tenant, not the vendor’s.
3. Vendor access nobody inventoried
In Ponemon Institute and Imprivata research, 47% of organizations reported a breach or attack involving third-party network access in the past year, yet only 50% keep a comprehensive inventory of vendors with network access.5 Access that is not listed is not reviewed.
4. Patch speed under pressure
Exploited vulnerabilities overtook stolen credentials as an initial access vector in the 2026 DBIR, at 31% of breaches.1 A written patching policy says little about how fast a vendor closes an exploited flaw on an appliance sitting in front of your data.
5. The fourth party behind the vendor
Your vendor’s hosting provider, identity platform, and software dependencies sit outside your contract and usually outside the questionnaire. When one of them is compromised, the exposure travels downstream.
The Cost, and the Confidence Gap
IBM’s 2026 Cost of a Data Breach Report puts the global average breach at $4.99 million.6 Supply chain compromise ranked first among 30 cost factors, adding $227,250 and averaging 258 days to identify and contain.7 Leaders see the risk: 86% express concern about supply chain risk, yet 90% are confident their business could keep operating through a vendor breach.8 Those two findings are hard to reconcile without continuous evidence.

Figure: Leaders report high concern and high confidence at once, while practice lags: 67% still rely on point-in-time audits and only 50% fully inventory vendor access. Sources: SecurityScorecard (2026); Ponemon Institute and Imprivata (2025).825
Disclosure makes it a board matter
For U.S. public companies, Regulation S-K Item 106(b) asks whether the registrant has processes to oversee and identify cybersecurity risks from its use of third-party service providers, and SEC staff have said stating that a process exists is not enough.9 Vendor oversight is now a disclosed control. In Devensa AI, this is the territory of the vCISO capability, an AI-powered vOfficer augmented by Devensa subject-matter experts where needed, designed to connect vendor security evidence to the governance record a board reviews.
NIST CSF 2.0 Moved Supply Chain Into Govern
NIST’s Cybersecurity Framework 2.0 placed Cybersecurity Supply Chain Risk Management (GV.SC) inside its new Govern function. The category expects an established supply chain risk program, suppliers prioritized by criticality, security requirements written into contracts, and assessment and monitoring across the full relationship, including its end. Zero Trust principles carry this to the technical layer: vendor access is verified continuously, scoped to the task, and never trusted because of where it originates.
Devensa AI scores this through TruMaturity™, the methodology and six governance domains shared across Devensa. On the platform, the TruMaturity™ Assessment is designed as an AI-mediated, adaptive assessment, triggered on first sign-in and roughly annually after that, with scores mapped to the five CMMI maturity levels. For third-party security, the levels read like this:
- Level 1, Initial: Vendors are onboarded through procurement with no security review.
- Level 2, Managed: Questionnaires are collected at onboarding and filed.
- Level 3, Defined: Vendors are tiered by criticality, and review depth matches the tier.
- Level 4, Quantitatively Managed: Access, integrations, and external signals are monitored against thresholds.
- Level 5, Optimizing: Incidents and findings reshape contracts, tiering, and access design.
Closing the Gap Between Attestation and Evidence
- Tier before you ask. Send deep questionnaires only to vendors whose compromise would be material, and lighter screens to the rest.
- Inventory access from your side. Pull service accounts, VPN users, and OAuth grants from your own systems, then reconcile them against the vendor list.
- Ask for evidence, not answers. Request SOC 2 Type II reports, penetration test summaries, and proof of MFA enforcement for in-scope systems.
- Monitor between reviews. External attack surface changes, leaked credentials, and breach disclosures often signal drift well before the next questionnaire.
- Rehearse the vendor breach. Include a critical supplier compromise in tabletop exercises and confirm who calls whom.
Frequently Asked Questions
What do vendor security questionnaires miss?
They miss live configuration, the permissions your own tenant has granted to vendor integrations, fourth-party dependencies, and anything that changes after the answers are returned. They record attestations, which support screening but are not evidence of enforced controls.
Are questionnaires still worth sending?
Yes, as a screening and contractual tool. A signed attestation records what the vendor represented. The problem arises when the questionnaire is treated as the whole program rather than the first step.
How is third-party risk different from supply chain risk?
The terms overlap. Third-party risk usually refers to direct vendors and service providers. Supply chain risk extends to the software components, hardware, and fourth-party providers behind them. NIST CSF 2.0 addresses both under GV.SC.
What does continuous vendor monitoring involve?
It pairs external signals, such as exposed services, leaked credentials, and breach disclosures, with internal signals, such as active vendor accounts and integration permissions. It supplements periodic reviews rather than replacing them.
Who should own third-party security risk?
Security typically owns the assessment method, while the business owner of each vendor relationship owns the decision to accept residual risk. Gartner recommends tracking those contract decisions so risk acceptance is visible.10 If a critical vendor were breached tonight, who in your organization would know first?
| Replace the Snapshot With a Record Devensa AI is a multi-tenant governance platform preparing for launch. Its vCISO capability, an AI-powered vOfficer augmented by Devensa subject-matter experts where needed, is designed to connect vendor security evidence to NIST CSF 2.0 expectations and score the results within TruMaturity™. Schedule a demo to see how it is structured. For a self-serve start, the free Governance Readiness Assessment is planned for devensa.ai. How many of the vendors with access to your environment today have you reviewed since they were onboarded? Schedule a demo: info@devensa.ai | Early access and the Governance Readiness Assessment: devensa.ai |
Sources
1. Verizon, “Breach entry point, 2026 DBIR finds” (2026 Data Breach Investigations Report news release, May 19, 2026). https://www.verizon.com/about/news/breach-industry-wide-dbir-finds
2. Vanta via Stacker (KVIA), “Third-party data breaches rose 60% in a year. Most vendor reviews still happen once,” citing SecurityScorecard 2026 Supply Chain Cybersecurity Trends Report (September 2026). https://kvia.com/stacker-cybersecurity-privacy/2026/09/23/third-party-data-breaches-rose-60-in-a-year-most-vendor-reviews-still-happen-once/
3. dmarcian, “2026 Verizon Data Breach Investigations Report: Strong foundations in the face of change,” summarizing Verizon 2026 DBIR third-party findings (2026). https://dmarcian.com/2026-verizon-data-breach-investigations-dmarc/
4. Abnormal AI, “Key Takeaways From Verizon 2026 DBIR,” summarizing Verizon 2026 DBIR (June 2026). https://abnormal.ai/blog/blog-verizon-2026-dbir-key-takeaways
5. Ponemon Institute and Imprivata, “The State of Third-Party Access in Cybersecurity” (2025), report infographic. https://www.imprivata.com/sites/imprivata/files/2025-06/3214-2025_Ponemon%20TPA%20report%20Infographic.pdf
6. IBM and Ponemon Institute, Cost of a Data Breach Report 2026, key findings as reported by eSecurity Planet (July 30, 2026). https://www.esecurityplanet.com/cybersecurity/ibm-2026-cost-of-a-data-breach-report-key-findings/
7. IBM and Ponemon Institute, Cost of a Data Breach Report 2026, supply chain cost-factor findings as analyzed by Cycode (August 6, 2026). https://cycode.com/blog/ibm-cost-of-data-breach-2026/
8. SecurityScorecard, 2026 Supply Chain Cybersecurity Trends Report (2026). https://securityscorecard.com/resources/research/2026-supply-chain-cybersecurity-trends-report/
9. BDO, “SEC Cybersecurity Rules: A Snapshot,” covering Regulation S-K Item 106 and SEC staff observations (April 2025). https://bdo.com/getmedia/a2f8e596-7382-4a1e-82e3-891816e22dfe/SEC-Cybersecurity-Rules-A-Snapshot.pdf?ext=.pdf
10. Gartner, “Gartner Survey Finds 45% of Organizations Experienced Third Party-Related Business Interruptions During the Past Two Years” (December 13, 2023). https://www.gartner.com/en/newsroom/press-releases/2023-12-13-gartner-survey-finds-45-percent-of-organizations-experienced-third-party-related-business-interruptions-during-the-past-two-years
11. Verizon, 2025 Data Breach Investigations Report, Executive Summary (2025). https://www.verizon.com/business/resources/reports/2025-dbir-executive-summary.pdf
This article is provided for informational purposes only and does not constitute legal or compliance advice. Consult qualified counsel before making governance decisions.


Responses