CVE-2007-0671 is an excel remote code execution vulnerability in Microsoft Office. CISA added it to the Known Exploited Vulnerabilities catalogue on 12 August 2025, which means attackers have used it in real attacks. Microsoft Office Excel contains a remote code execution vulnerability that can be exploited when a specially crafted Excel file is opened.
What Makes This CVE Dangerous
CVE-2007-0671 matters because it turns a routine document-open action into code execution inside Microsoft Office Excel. That is dangerous in practice because the file format is familiar, easy to deliver, and often trusted by users and mail gateways.
For defenders, the key issue is not just that the flaw exists, but that exploitation begins at the moment a crafted spreadsheet is opened. Once code runs in the context of the user or application, the attacker can often chain the initial foothold into broader compromise, depending on the privileges and connectivity of the endpoint.
How Organisations Check Exposure
Exposure review starts with a complete inventory of Microsoft Office deployments, the versions in use, and the systems where Excel files are routinely opened, especially mail-enabled desktops, analyst workstations, and shared business endpoints. Organisations should also look for external exposure to file delivery channels, since the attack depends on getting a malicious workbook to a target.
Authoritative version and patch details belong in the vendor advisory and the CISA Known Exploited Vulnerabilities catalogue, not in informal summaries. The public CVE record and the national vulnerability database help teams confirm identification and prioritisation, while internal asset data shows which users and systems are actually at risk.
External references: CVE Program and NIST National Vulnerability Database.
Remediation and Compensating Controls
The preferred response is to apply the vendor fix as soon as it is validated in your environment. When that is not immediately possible, reduce exposure by restricting where Excel files come from, blocking untrusted attachments where feasible, and limiting automatic content handling that can make malicious files easier to reach users.
Compensating controls should focus on blast-radius reduction. That means keeping local privilege low, segmenting high-value workstations, hardening email and web download paths, and treating spreadsheet files from outside the organisation as potentially executable payloads rather than harmless data.
For deeper vulnerability triage and remediation workflow context, see Vulnerability Management Guide.
Detection and Post-Exploitation Review
Detection should look for unusual Excel launches followed by suspicious child processes, script execution, or network activity that does not fit the user’s normal workflow. If exploitation is suspected, review endpoint telemetry, email gateways, and download logs for the original document path and any second-stage activity.
After patching, organisations should still investigate whether the vulnerable file was opened before the fix was applied. A successful exploit can leave behind persistence, credential exposure, or follow-on malware, so patching alone is not a substitute for compromise review.
Use MITRE ATT&CK Enterprise Matrix to map observed post-exploitation behaviour to known techniques and detection opportunities.
Risk and Threat Considerations
This CVE is attractive to attackers because it can be delivered through a document that users expect to open, which makes initial access easier to achieve than many perimeter exploits. The real danger is not only code execution, but the ability to convert a single file open into a larger intrusion path.
Failure mechanism: A crafted spreadsheet triggers code execution when Excel processes the file, allowing the attacker to run payloads in the user’s context and potentially pivot into the rest of the environment.
Impact: The compromise can expose local data, credentials, and access to internal resources, and it can create a foothold for persistence, lateral movement, or further malware deployment.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
CIS Controls v8 and NIST SP 800-53 Rev 5 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | CVE exploitation requires continuous exposure tracking and remediation prioritisation. |
| CIS-10 — Malware Defenses | Malicious spreadsheets often deliver payloads through endpoint execution paths and email. | |
| Recommendation — Prioritise this KEV-listed Excel flaw for rapid remediation and exception handling. Harden email and endpoint controls to block malicious Office file delivery and execution. | ||
| NIST SP 800-53 Rev 5 | SI-3 — Malicious Code Protection | The vulnerability is exploited through a crafted file that can deliver malicious code. |
| SI-2 — Flaw Remediation | A KEV-listed RCE requires timely remediation and verification after patching. | |
| AU-6 — Audit Review, Analysis, and Reporting | Post-exploitation review depends on analyzing endpoint and email telemetry for abuse. | |
| Recommendation — Deploy malicious-code protections on file ingress and endpoint execution paths. Track this Excel vulnerability through remediation, validation, and exception closure. Review telemetry for suspicious Office process chains and file-open activity. | ||
Practitioner Guidance
Why practitioners should care: Older CVEs that remain in active exploitation deserve fast prioritisation, especially when the trigger is a common user action like opening a file. Treat KEV-listed document-processing flaws as exposure-management problems, not just patch tickets.
What to watch for: Pay attention to business units that exchange spreadsheets externally, executives and analysts who receive high-volume email, and endpoints where software is slow to update. Those are often the most practical entry points for this kind of flaw.
Practitioner takeaway: If you cannot patch immediately, narrow the file-delivery surface and increase monitoring on the endpoints most likely to open the malicious workbook first.