5 critical steps to strengthen cybersecurity in M&A

Cybersecurity in mergers and acquisitions has become one of the most decisive yet least understood factors shaping deal success, integration speed, and long-term risk.

As M&A activity remains elevated heading into 2026, organizations face growing pressure to move quickly, integrate sooner, and demonstrate value faster.

While successful mergers and acquisitions can promise rapid scale and transformation, they also introduce a highly underestimated threat: identity security risk. Access often expands faster than governance, visibility decreases during transition, and identity decisions made under time pressure can become permanent before their impact is fully understood.

These environments are prime targets for cyberattacks, with orphaned accounts, unmanaged applications, and fragmented policy enforcement treated as high-priority targets. There are five critical identity risk inflection points across the three phases of the acquisition lifecycle—pre-acquisition, during acquisition, and post-acquisition—and CISOs can either preserve continuity or create long-term exposure that lingers well beyond integration.

1. Pre-acquisition: Visibility is assumed, not verified

The first critical decision comes before any agreements are signed: how deeply to examine the target company's identity infrastructure.

Traditional due diligence often evaluates what’s documented rather than what’s enforced, leaving leaders to approve deals without a clear view of who has access to what, where, and why. Risks such as orphaned accounts, overprovisioned entitlements, inconsistent policy enforcement, and gaps between documented controls and real-world access behavior are often overlooked.

This gap creates immediate downstream risk. Orphaned identities may retain access long after departure. Overprovisioned entitlements quietly violate least-privilege principles. Inconsistent policy enforcement introduces compliance and regulatory risks that are rarely captured in standard questionnaires. All this forces CISOs to inherit risks they never consciously accepted.

More disciplined acquirers address this by shifting from point-in-time checks to continuous evidence-based identity discovery that exposes gaps between documented policy and enforced access. The challenge is to expose those gaps without slowing deal momentum—an area where many organizations discover their diligence processes fall short.

2. Deal announcement to close: Temporary access becomes a permanent risk

The period between deal announcement and close, often referred to as the during-acquisition phase, is a fragile security environment in the M&A lifecycle.

During this critical window, temporary access arrangements often become permanent by default. Cross-organizational trust extends without unified governance. Privileged access grows faster than oversight can keep pace. What seems necessary for business continuity can quickly become persistent security gaps.

The challenge intensifies because M&A creates scenarios in which access must increase before controls can consolidate, making identity one of the most heavily exploited attack vectors

Organizations that struggle during this phase rely on standard access models that weren’t designed for transitional environments. Those that succeed recognize that M&A introduces a fundamentally different access problem, requiring deliberate governance choices to avoid embedding risk in the foundation of the combined organization.

3. Post-acquisition (early integration): Creating identity debt

Pressure to show fast integration progress often pushes security teams into risky shortcuts. As business leaders demand visible wins, access models may be merged before identity controls are fully understood. Legacy identity debt from both organizations can collide, increasing complexity and reducing visibility.

These early shortcuts create identity debt that compounds over time. Temporary decisions harden into structural weaknesses. Misaligned access persists as systems scale. Reversing these decisions later becomes exponentially more difficult as dependencies increase, and disruption risk grows.

Resilient organizations recognize this inflection point and resist equating speed with consolidation. Instead, they treat early integration as a phase that demands heightened visibility and restraint, knowing that the identity decisions made at that time may define operational security for years to come.

4. Post-acquisition: Speed of sprawl

Once a deal closes, identity sprawl accelerates. This post-acquisition period is a narrow window in which identity decisions can impose order or allow sprawl to complicate the operating model. Every unresolved access issue becomes harder to unwind as the organization stabilizes and scales.

Audit and compliance expectations rise during acquisition and intensify immediately after close. Regulators and internal stakeholders expect clear, verifiable governance across the combined environment, even as teams are still gaining visibility and control is spread across systems.

Organizations that fail to establish enforceable identity governance early often find that post-acquisition risk isn’t the result of a single failure but of many small access decisions left unresolved.

5. Post-acquisition (ongoing): Continuous monitoring

Security incidents tied to M&A activity may occur months after deal completion, when organizations assume integration risks have been resolved. There is a false sense of security that comes from treating identity assessment as a one-time activity.

M&A changes the identity attack surface, creating new pathways and relationships that didn't exist in either organization before. Without continuous visibility into this evolving environment, privileged access expands beyond appropriate boundaries, security gaps persist undetected, and incident response becomes fragmented across multiple systems and processes.

The organizations that maintain stability are those that continue to monitor identity behavior long after integration milestones are met.

They recognize that identity risk doesn’t disappear when the deal closes; it evolves

Ready to go deeper?

If you’re responsible for protecting deal value before, during, and after an acquisition, our full guide offers the operational depth this overview only touches on.

Download our comprehensive white paper—Securing Identities in Mergers and Acquisitions—for phase-specific guidance, practical checklists, and real-world examples that help organizations successfully navigate acquisition scenarios.