Third-party cookies create risk because they enable tracking across sites, often without clear user understanding, consent, or control. That raises compliance pressure under privacy laws and increases exposure if collected data is misused, leaked, or tied to session hijacking. The risk is not only legal. It also undermines user trust when organisations cannot explain who tracks them and why.
How Third-Party Cookies Create a Compliance Problem
Third-party cookies are risky because they often function as cross-site tracking infrastructure, which means the same identifier can follow a person across multiple properties without a clear, narrowly scoped purpose. That makes consent, notice, retention, and purpose-limitation harder to defend, especially where regulators expect a genuine understanding of who is processing data and why. ISO/IEC 27002:2022 Information Security Controls is a useful control reference for aligning tracking use with governance, logging, and privacy-aware handling.
Organisations also inherit compliance risk from the ecosystem around the cookie. Adtech partners, tag managers, analytics platforms, and embedded scripts can change over time, so the organisation may no longer have the same visibility into where identifiers travel or what downstream parties infer from them. That creates audit pressure because the legal question is not just whether a cookie exists, but whether the organisation can explain the full data flow and control it consistently.
One of the strongest signals of how material this issue has become is that NHI Mgmt Group’s Ultimate Guide to Non-Human Identities reports that 92% of organisations expose NHIs to third parties, which is a good reminder that third-party dependencies often widen governance and accountability gaps. For cookie-heavy environments, the same pattern shows up as weak oversight of integrations that collect or relay user data.
Why Third-Party Cookies Also Raise Security Exposure
Security risk appears when a cookie becomes part of a trust chain rather than a simple preference mechanism. If a third-party script, tag, or integration is compromised, it can be used to observe behaviour, redirect users, inject malicious content, or harvest session-linked information. That is why cookie risk is not only about privacy, it is also about the security consequences of placing trust in externally sourced client-side code and identifiers.
The danger increases when the cookie is associated with authentication or session state, because interception or reuse can support session hijacking, account takeover, or unauthorized access. Even when the cookie itself is not a login credential, it may still be a signal that helps correlate users, profiles, or transactions across systems, which increases the value of the data if it leaks or is repurposed by an attacker.
Supply-chain controls matter here because third-party cookies often depend on third-party JavaScript and services. A practical control baseline is to treat every external tag or script as an active dependency, not just a marketing asset, and to verify that it cannot silently expand collection scope. NIST SSDF (SP 800-218), SLSA, and OpenSSF all reinforce the broader principle that integrity, provenance, and dependency governance are core security concerns, not optional extras.
Practitioner Guidance for Reducing Third-Party Cookie Dependence
What to prioritise: Map every third-party cookie to a business purpose, a legal basis, and an owner who can explain why it exists. If you cannot clearly name the purpose and the downstream recipient, treat the cookie as a governance exception rather than a routine implementation detail.
What to verify: Confirm whether any cookie is tied to authentication, session continuity, cross-site profiling, or audience sharing. Those cases deserve stricter review than ordinary analytics cookies because they can turn a marketing control into an access or exposure issue.
What good looks like: The organisation can disable or replace third-party cookies without breaking core service delivery, and it can show that consent, retention, and vendor oversight are enforced consistently across all pages and tags.
Practitioner takeaway: The key test is not whether third-party cookies are common, it is whether you can prove they are bounded, disclosed, and non-essential to trust or access before you rely on them at scale.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK address the attack surface, NIST CSF 2.0 and CIS Controls v8 set the technical controls, and ISO/IEC 42001:2023 define the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| ISO/IEC 42001:2023 | GOVERN — AI Management System Governance | AI-adjacent tracking and profiling need governed purpose, accountability, and oversight. |
| Recommendation — Define accountable ownership for third-party tracking and review approved uses against stated purposes. | ||
| NIST CSF 2.0 | GV.RM — Risk Management Strategy | Third-party cookies create privacy, trust, and dependency risk that needs formal treatment. |
| PR.DS — Data Security | Cookies can expose identifiers, session data, and tracking signals that need controlled handling. | |
| PR.AC — Identity and Access Management, Access Control | Cookie misuse can support session hijacking and unauthorized access when tied to user sessions. | |
| Recommendation — Classify cookie dependencies in risk registers and set acceptance criteria for external tracking. Limit collection, retention, and sharing of cookie-derived data to the minimum necessary. Protect session-bearing cookies with strong browser and server-side access controls. | ||
| CIS Controls v8 | 15 — Service Provider Management | Third-party cookies rely on external providers and scripts that must be governed as suppliers. |
| Recommendation — Inventory third-party trackers and require contractual and technical oversight of their data collection. | ||
| MITRE ATT&CK | T1185 — Browser Session Cookie | Third-party cookie exposure can enable hijacking or abuse of browser session state. |
| T1199 — Trusted Relationship | The risk comes from abusing trusted third-party scripts, tags, and integrations. | |
| Recommendation — Monitor for cookie theft and session reuse patterns that indicate browser-session compromise. Assume third-party tracking code is a trusted relationship that can be abused and validate it continuously. | ||
Related resources from NHI Mgmt Group
- Why do third-party vendors create such high compliance and security risk for organisations?
- Why does third-party access create outsized risk when organisations rely on vendors, bots, and contractors with connected systems?
- Why do third-party health apps create a larger privacy and security risk than internal systems?
- Why do third-party SDKs create mobile security risk even when features are disabled?
Deepen Your Knowledge
Reviewed and updated by the NHIMG editorial team on September 18, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org
