How do you patch or mitigate CVE-2015-2545 (Microsoft Office Malformed EPS File)?

By NHI Mgmt Group Editorial Team Updated October 19, 2026 Domain: Cyber Security

CISA's required action for CVE-2015-2545 is to apply updates per vendor instructions. In practice, find every instance of Microsoft Office in your estate, apply the vendor security update or documented mitigation, and if no fix can be applied, remove internet exposure or take the product out of service. After patching, review logs for signs of earlier exploitation, because attackers used this flaw in the wild.

How should you patch Microsoft Office for CVE-2015-2545?

The safest response is to treat this as an exploited, high-priority Office exposure. Start by locating every Microsoft Office installation, then apply the vendor security update exactly as directed by Microsoft. If you cannot patch immediately, remove internet exposure, isolate the affected systems, or take the product out of service until you can.

That approach matters because file-format vulnerabilities in desktop productivity software are often reachable through ordinary email and document handling workflows, so “patch later” is usually not a safe plan once the flaw is known to be exploited.

What to do if patching is delayed or blocked

When patching cannot happen on schedule, the decision is not whether to accept the risk, but how to reduce the blast radius. Restrict who can open external documents, harden email and web-delivery paths that feed Office files, and keep the vulnerable version off exposed endpoints where untrusted content can reach it. Use this window to confirm whether any business process still depends on that installation.

If the affected software must remain online for a short period, the mitigation should be operationally explicit and temporary. Put compensating controls in place that materially reduce inbound document exposure, then track the exception to closure rather than letting it become a standing waiver.

How do you check for compromise after exposure?

After remediation, review endpoint, email, and application logs for signs that the vulnerability was exercised before the fix landed. Because the flaw was used in the wild, the question is not only whether the patch was applied, but whether malicious content was opened, rendered, or delivered through the normal document workflow before containment.

Look for unusual document opens, suspicious child processes launched from Office, unexpected downloads, and any later activity that suggests a document-based foothold. If you find evidence that the vulnerable path was used, treat the event as a potential initial-access incident and widen the investigation beyond the patched host.

Risk and Threat Considerations

This vulnerability is dangerous because it sits in a high-trust document handling path, which makes exploitation practical in environments where Office files are routinely received from outside the organisation. The main risk is that a user action as ordinary as opening a file can become an entry point for code execution or follow-on compromise.

Failure mechanism: Malformed content is processed by Office before the user can judge whether the document is safe, so the attacker relies on trusted workflow and document rendering to deliver the exploit.

Impact: Successful exploitation can create initial access on a user endpoint, expose local data, or provide a foothold for broader intrusion, which is why post-patch hunting is part of the remediation task.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

CIS Controls v8, NIST CSF 2.0, NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.

Framework	Control / Reference	Relevance
CIS Controls v8	CIS-7 — Continuous Vulnerability Management	Prioritizes patching and mitigation for actively exploited software flaws.
Recommendation — Prioritise and verify remediation of the Office vulnerability across the asset estate.
NIST CSF 2.0	PR.IP-12 — Vulnerability Management Plan	Requires managing known vulnerabilities through planned remediation and exceptions.
Recommendation — Track the Office fix as a managed vulnerability and close any exception quickly.
NIST SP 800-53 Rev 5	SI-2 — Flaw Remediation	Directly governs applying vendor updates and mitigations for software flaws.
	SI-4 — System Monitoring	Supports post-remediation log review and compromise detection after exploitation.
Recommendation — Apply the vendor update or approved mitigation for the affected Office installation. Review logs and alerts for evidence of pre-patch exploitation or persistence.
OWASP ASVS	V13 — Configuration	Supports reducing exposure by removing or constraining vulnerable deployment paths.
Recommendation — Remove or constrain exposed installations until the vulnerable Office path is remediated.

Practitioner Guidance

What to prioritise: Patch every reachable Office instance first, then verify that no unmanaged or forgotten endpoint still has the vulnerable software exposed to external documents. If you cannot patch all systems at once, prioritise the systems most likely to open mail or internet-sourced files.

What to verify: Confirm the vendor update or documented mitigation actually removed the exposure, and do not assume the issue is gone just because one workstation was remediated. A complete response includes proof that the vulnerable build is absent or the risky surface is no longer reachable.

Practitioner takeaway: For exploited document-processing flaws, remediation is only half the job, because containment and compromise review are what separate a patch from a safe outcome.

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NHIMG Editorial Note
Reviewed and updated by the NHIMG editorial team on October 19, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org