Yes. CISA added CVE-2021-31199 to its Known Exploited Vulnerabilities catalogue on 3 November 2021, which it does only when there is reliable evidence of active exploitation. CISA has not linked it to known ransomware campaigns. Microsoft Enhanced Cryptographic Provider contains an unspecified vulnerability that allows for privilege escalation. Any organisation running the affected product should treat remediation as urgent.
What “Exploited in the Wild” Means for This CVE
CISA’s KEV listing is the key signal here: it indicates that CVE-2021-31199 has reliable evidence of active exploitation, not just theoretical risk. For responders, that changes the question from “should we patch?” to “how quickly can we confirm exposure, contain the blast radius, and verify whether the affected system has already been used as an entry point or privilege-escalation path?”
For a Microsoft vulnerability that allows privilege escalation, the practical concern is whether an attacker can turn a foothold into elevated rights on the same host or adjacent systems. That is often enough to justify emergency handling, because privilege escalation can be chained with credential theft, persistence, or lateral movement before defenders notice.
When you triage a KEV-listed issue, the most important distinction is between “patched eventually” and “actively being abused now.” The latter requires urgent exposure validation, remediation, and hunting for suspicious post-exploitation activity rather than waiting for a routine maintenance window.
See CISA’s Known Exploited Vulnerabilities Catalog for the authoritative exploitation status and NIST National Vulnerability Database and the vendor advisory for product-specific remediation details.
How to Confirm Exposure and Reduce Immediate Risk
Start by identifying every system where Microsoft Enhanced Cryptographic Provider is present and confirm whether it is in the scope of your standard hardening, patch, and asset inventory processes. If a vulnerable component is present on internet-facing systems, authentication hosts, or admin workstations, treat it as higher priority than the same issue on low-trust internal endpoints.
If remediation cannot happen immediately, focus on compensating controls that reduce the attacker’s ability to capitalize on escalation. That means restricting administrative logon paths, tightening local privilege boundaries, and increasing monitoring on the affected hosts for unusual process launches, new privileged sessions, and suspicious account changes.
Because the flaw is tied to privilege escalation, exposure is not limited to the vulnerable binary itself. You should also assess whether the affected system stores reusable credentials, has cached privileged sessions, or can reach management tools and sensitive services that would let an intruder move from one elevated foothold to a broader compromise.
The Vulnerability Management Guide is useful here because KEV-listed issues should move through an accelerated prioritisation path, with explicit verification that the vulnerable asset is fixed and not just assigned to a queue. The same urgency principle is reinforced in the Zero-Day and Exploited Vulnerabilities Guide, which covers KEV triage, emergency mitigation and post-patch hunting.
What to Check After Remediation
After patching or mitigating, do not stop at configuration closure. Look for signs that the vulnerable host was already used for privilege escalation, such as unexpected local administrators, altered security groups, new services, unusual scheduled tasks, and evidence of outbound connections that do not fit normal administrative behavior.
If the affected system handled sensitive credentials or administrative sessions, rotate what it may have exposed. That includes passwords, tokens, service credentials, and any other secrets that could have been accessed after an attacker obtained elevated rights.
Where the system is part of a privileged access path, review whether the compromise could have enabled broader domain or cloud access. A local escalation bug becomes strategically important when it sits next to admin tooling, remote management interfaces, or systems that can laterally reach high-value targets.
Risk and Threat Considerations
Active exploitation means the risk is operational, not hypothetical: attackers can combine a local privilege-escalation flaw with existing access, stolen credentials, or a weak service account to deepen control before defenders respond. The main danger is not only initial compromise, but the speed at which a low-level foothold can become administrative control.
Failure mechanism: An attacker gains execution or a foothold on the affected host, uses the escalation flaw to obtain higher privileges, then pivots to credential access, persistence, or lateral movement while appearing to be a legitimate administrator.
Impact: The result can be full host compromise, unauthorized access to protected data or services, and a materially larger incident because the attacker has moved from user-level access to trusted-system control.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
MITRE ATT&CK addresses the attack and risk surface, while CIS Controls v8, NIST CSF 2.0 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 | Active exploitation makes rapid vuln prioritisation and remediation central. |
| Recommendation — Prioritise and remediate KEV-listed vulnerabilities on an emergency timeline. | ||
| NIST CSF 2.0 | GV.RM-01 — Risk Management Strategy | KEV status requires risk-based escalation and accelerated treatment. |
| Recommendation — Classify KEV-listed vulns as urgent and route them through risk-based remediation. | ||
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | The issue requires rapid remediation of an exploited software flaw. |
| AU-6 — Audit Record Review, Analysis, and Reporting | Post-exploitation review depends on finding suspicious privileged activity. | |
| Recommendation — Patch or mitigate the vulnerable component without waiting for the next routine cycle. Review logs for unusual administrative actions and post-exploitation behavior. | ||
| MITRE ATT&CK | T1068 — Exploitation for Privilege Escalation | The CVE is explicitly a privilege-escalation vulnerability. |
| Recommendation — Hunt for exploitation paths that elevate an existing foothold to higher privileges. | ||
Practitioner Guidance
What to prioritise: Treat KEV-listed exploitation as a response event, not a routine patch item. The first priority is asset confirmation, because the wrong assumption is often that “this host was probably already patched.”
What to verify: Validate whether the vulnerable component is present, whether the host has privileged reach, and whether any credentials or management channels on that system should be rotated after remediation. If the system sits on a critical trust boundary, investigate for compromise before declaring closure.
Practitioner takeaway: For an actively exploited privilege-escalation CVE, the real decision is whether you are still preventing further abuse or already responding to an incident that has been in progress long enough to leave traces.
Related resources from NHI Mgmt Group
- Is CVE-2021-31201 (Microsoft Enhanced Cryptographic Provider Privilege Escalation) being exploited in the wild?
- How do you patch or mitigate CVE-2021-31199 (Microsoft Enhanced Cryptographic Provider Privilege Escalation)?
- CVE-2021-31199 (Microsoft Enhanced Cryptographic Provider Privilege Escalation)
- CVE-2021-31201 (Microsoft Enhanced Cryptographic Provider Privilege Escalation)