Why Old Vulnerabilities and Third-Party Access Are as Dangerous as Phishing

Phishing still matters and it remains one of the most common entry points for attackers. But in 2026, it is no longer the only or even always the most reliable path to compromise. Increasingly, attackers are just as likely to succeed by exploiting unpatched systems or abusing trusted third-party access as they are by sending a convincing phishing email.

For many organizations, the real risk is not choosing between these vectors it is underestimating how equally dangerous they have become.

Verizon’s 2025 DBIR shows that exploitation of vulnerabilities as an initial access vector reached 20%, marking a 34% increase year over year, while third-party involvement appeared in 30% of breaches. Attackers are no longer relying only on human error; they are equally exploiting technical exposure and trust relationships that already exist.

The real question for security leaders

This shift changes the conversation. The question is no longer only: “How do we stop phishing?”

It must now also include:

• Which exposed systems could be exploited just as easily as a phishing click?

• Which third-party relationships create access comparable to a compromised user account?

NIST frames patch management as preventive maintenance that reduces the likelihood of compromise, while its supply-chain guidance highlights a persistent lack of visibility into how third-party services are built, secured, and operated.

The implication is clear: technical exposure and third-party access must be treated with the same urgency as phishing risk.

The combined risk that organizations overlook

In practice, the biggest cybersecurity risk for many companies in 2026 is the combination of:

• known exploitable vulnerabilities

• and overtrusted third-party access

CISA’s Known Exploited Vulnerabilities (KEV) Catalog exists specifically to highlight vulnerabilities that are already being used in real attacks. That makes them just as actionable and often just as dangerous, as phishing campaigns targeting employees.

Treating phishing as the “main threat” while relegating vulnerabilities and vendors to secondary concerns creates an artificial gap in defense. Attackers do not think in silos, they choose whichever path is easiest.

Why attackers treat these vectors equally

Attackers optimize for success. A phishing campaign depends on user behavior. Exploiting a known vulnerability or abusing a trusted supplier connection often does not.

This is why vulnerability exploitation continues to grow, especially in internet-facing systems, VPNs, and edge devices. These assets shorten the path from discovery to compromise, sometimes even more reliably than phishing.

At the same time, modern organizations rely on ecosystems of SaaS platforms, cloud providers, MSPs, and contractors. These relationships introduce trusted access which, if mismanaged, can be just as powerful as compromised credentials obtained through phishing.

The risk is not just that a vendor gets breached. The risk is that their access becomes equivalent to an attacker successfully phishing your employee.

Why patch management is as critical as phishing defense

Patch management has always been important, but in 2026 it plays a role equal to user awareness and email protection.

NIST defines patch management as a full lifecycle process: identifying, prioritizing, applying, and verifying updates. This makes it a core security function — not just IT maintenance.

The key shift is this: effective patching is not about volume, but about reducing real-world exploitability.

Just as phishing programs focus on high-risk user behaviors, patching must focus on:

• actively exploited vulnerabilities

• internet-facing systems

• identity and access infrastructure

CISA guidance reinforces this by emphasizing remediation of known exploited vulnerabilities as a priority, not just high CVSS scores.

Why CVSS alone is not enough

Many organizations still prioritize vulnerabilities purely by severity. That approach is incomplete.

CVSS describes technical impact, but not whether attackers are actually using a vulnerability.

That is why KEV matters. A vulnerability actively exploited in the wild represents a risk level comparable to an active phishing campaign targeting your employees.

A stronger prioritization model asks:

• Is it being exploited?

• Is the asset exposed or critical?

• What happens if it is compromised?

This aligns vulnerability management much closer to real attacker behavior — the same way phishing simulations align with real social engineering tactics.

Why third-party access must be treated like user risk

Third-party risk is often underestimated because it is framed as a compliance issue rather than an access issue.

In reality, vendors often have:

• administrative access

• remote support channels

• API integrations

• identity federation

• access to sensitive data or systems

This makes them functionally equivalent to privileged internal users and therefore just as attractive as phishing targets.

If phishing compromises a user, an attacker gains access. If a vendor is compromised or overprivileged, the result can be the same.

That is why third-party risk must be treated as: identity, access, and trust management, not just vendor management.

What organizations should verify before granting access

A modern vendor security review should ensure that third-party access does not introduce risks equivalent to compromised credentials.

Key areas to verify include:

• access scope and limitations

• least-privilege design

• MFA enforcement

• monitoring and logging of sessions

• vulnerability and patching practices

• incident response capabilities

• contractual obligations

• offboarding processes

These controls mirror internal security practices because third-party access should be treated with the same level of scrutiny as internal users.

How Blue Teams should prioritize

Blue Teams should shift toward exposure-centric defense, where phishing is one of several equally important entry points.

That includes prioritizing:

• internet-facing systems

• remote access infrastructure

• identity systems

• SaaS integrations

• third-party access

Alongside:

• phishing detection and awareness

The goal is not to reduce phishing risk alone, but to reduce all realistic paths to compromise.

Where Red Team brings clarity

Red Team exercises are most valuable when they test whether:

• a vulnerability can be exploited as easily as phishing

• a vendor relationship can provide equivalent access

• multiple weak points can be chained into a real incident

The outcome should answer one question: which path would an attacker actually choose first: phishing, vulnerability, or third-party access?

In many cases, the answer is: any of them, whichever is easiest.

What GRC and compliance teams must change

GRC teams need to move beyond treating phishing, patching, and third-party risk as separate control domains.

Instead, they must demonstrate that the organization:

• understands all major entry points

• prioritizes based on real risk

• governs access consistently across users and vendors

• produces evidence of these decisions

Regulatory frameworks like DORA, NIS2, and NIST CSF 2.0 increasingly reflect this integrated view of risk.

What a mature 2026 strategy looks like

A mature cybersecurity strategy does not prioritize phishing over other risksб it aligns all major attack vectors:

• Phishing defenses reduce human risk

• Patch management reduces technical exposure

• Third-party governance reduces inherited risk

Together, they form a unified defense model focused on realistic attack paths.

Phishing is still a critical threat, but it is no longer uniquely dominant.

Old vulnerabilities and third-party access are now equally dangerous, often offering attackers faster or more predictable paths to compromise.

Organizations that treat these risks as separate or secondary create blind spots. Those that treat them as equivalent entry points build far more resilient defenses.

FAQ

Are old vulnerabilities as dangerous as phishing in 2026?

Yes. Many vulnerabilities are actively exploited in the wild, making them just as practical and dangerous as phishing attacks.

Why is third-party access comparable to phishing risk?

Because it often provides trusted, privileged access, similar to what attackers gain after successfully compromising a user account.

Should we prioritize phishing over patching?

No. Both should be treated as equally critical components of a broader risk management strategy.

How should organizations prioritize vulnerabilities?

By combining severity, exploitability, and asset context, not relying on CVSS alone.

Who owns this problem?

Security, IT, and GRC teams together, because this is not a single-vector risk, but a combined attack surface.