Yes. CISA added CVE-2013-1331 to its Known Exploited Vulnerabilities catalogue on 8 June 2022, which it does only when there is reliable evidence of active exploitation. CISA has not linked it to known ransomware campaigns. Microsoft Office contains a buffer overflow vulnerability that allows remote attackers to execute code via crafted PNG data in an Office document.
How to confirm whether CVE-2013-1331 is actively exploited
The right confirmation signal is not the CVE title alone, but whether it appears in CISA’s Known Exploited Vulnerabilities Catalog. For this CVE, that inclusion means the issue has crossed the threshold from theoretical exposure to observed exploitation, so the first question is always whether any Microsoft Office install in your estate can still process untrusted documents.
When a vulnerability is tied to document parsing, exposure often hides in places security teams under-scope too narrowly: desktop Office, shared mailboxes, preview panes, shared drives, and archived content that can still be opened by users or automation. The practical test is asset coverage, not product branding, because the exploit path depends on whether the vulnerable code path is reachable from real document handling.
What the exploit path means for defenders
This is a remote code execution problem in a widely deployed productivity application, so the main operational risk is that a crafted file can turn routine document handling into code execution. That changes triage priority because the attacker only needs a delivery path into normal user workflow, not administrative access or an exposed service endpoint.
For defenders, the useful security question is whether the vulnerable application is still trusted to open externally sourced content at all. In practice, that means treating email attachments, downloaded documents, and shared files as potential execution carriers until the vulnerable estate is reduced or removed.
What to do if patching or mitigation has to wait
If you cannot remediate immediately, contain the blast radius around document ingestion and document opening. Reduce exposure by tightening mail and web delivery paths, limiting who can receive and open external Office content, and increasing monitoring around document-originated process launches, child processes, and unusual Office behavior.
Where the flaw is materially exposed, review whether the same user population also has elevated access to sensitive systems. A document-based exploit becomes much more consequential when the affected endpoint already holds credentials, persistent sessions, or access to internal resources that can be reused after code execution.
Risk and Threat Considerations
Active exploitation means this is not only a patching issue, it is also a compromise-assessment issue. Attackers often use document-based remote code execution for initial access because it is compatible with normal business traffic and can be delivered through everyday file exchange.
Failure mechanism: A crafted PNG embedded in an Office document can trigger a buffer overflow when the application parses the content, allowing attacker-controlled code execution on the target system.
Impact: Successful exploitation can lead to endpoint compromise, follow-on credential theft, lateral movement, and further payload delivery, especially if the affected workstation is trusted or broadly privileged.
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 | Actively exploited Office CVEs require prioritized exposure reduction and remediation. |
| CIS-10 — Malware Defenses | Document-based exploitation often leads to payload delivery and endpoint compromise. | |
| CIS-13 — Network Monitoring and Defense | Exploitation may be visible through abnormal document-originated network or process activity. | |
| Recommendation — Prioritize and remediate the vulnerable Office exposure using risk-based vulnerability management. Harden endpoint and email defenses to detect malicious Office-delivered payloads. Monitor for suspicious traffic and process behavior that follows malicious document execution. | ||
| NIST CSF 2.0 | ID.RA-01 — Asset Vulnerabilities Are Identified and Recorded | Confirming exposure to an actively exploited CVE depends on identifying affected assets. |
| PR.IP-12 — Vulnerability Management | The question is about an actively exploited vulnerability and the need to remediate it quickly. | |
| DE.CM-01 — Networks and network services are monitored to find potential events | Active exploitation warrants monitoring for signs of compromise after document handling. | |
| Recommendation — Identify systems that can still reach the vulnerable Office parsing path. Remediate the vulnerability using a time-bound vulnerability management process. Monitor for post-exploitation indicators associated with malicious Office documents. | ||
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | This CVE requires applying the vendor fix or mitigation promptly. |
| SI-4 — System Monitoring | Document-based exploitation needs detection of suspicious endpoint activity after opening content. | |
| Recommendation — Apply the vendor remediation or approved mitigation without delay. Monitor endpoints for suspicious activity that follows Office document execution. | ||
| OWASP ASVS | V15 — Secure Coding and Architecture | The vulnerability is a buffer overflow, a secure software robustness concern. |
| Recommendation — Use secure design and memory-safety practices to prevent parser overflows. | ||
Practitioner Guidance
What to verify: Confirm whether any Office clients or virtual desktop images can still open externally sourced documents without compensating controls. If yes, treat them as exposed until you can prove otherwise, and prioritise systems that process inbound email or files from outside the organisation.
Decision rule: If you cannot patch immediately, do not wait for an observed alert before acting. Narrow document-handling exposure first, then hunt for suspicious Office process chains, unusual document creation times, and post-open activity that does not fit normal user behaviour.
Practitioner takeaway: For exploitable document-parsing flaws, the key question is not just whether a patch exists, but whether the vulnerable code path is still reachable by normal users and whether compromise indicators are already present.
Related resources from NHI Mgmt Group
- Guide: Zero-Day and Exploited Vulnerabilities Guide
- CVE-2013-1331 (Microsoft Office Buffer Overflow)
- Is CVE-2025-24993 (Microsoft Windows NTFS Heap-Based Buffer Overflow) being exploited in the wild?
- Is CVE-2013-2597 (Code Aurora ACDB Audio Driver Stack-based Buffer Overflow) being exploited in the wild?
- Is CVE-2025-20333 (Cisco Secure Firewall Adaptive Security Appliance (ASA) and Secure Firewall Threat Defense (FTD) Buffer Overflow) being exploited in the wild?