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PatchSiren cyber security CVE debrief

CVE-2021-31199 Microsoft CVE debrief

CVE-2021-31199 is a Microsoft Enhanced Cryptographic Provider privilege escalation vulnerability that CISA added to its Known Exploited Vulnerabilities catalog on 2021-11-03. Because it is in the KEV catalog, defenders should treat it as actively exploited or of confirmed exploitation concern and prioritize remediation using vendor guidance. The source corpus does not include deeper technical exploitation details, so the safest response is prompt patching and exposure review.

Vendor
Microsoft
Product
Enhanced Cryptographic Provider
CVSS
MEDIUM 5.2
CISA KEV
Listed
Original CVE published
2021-11-03
Original CVE updated
2021-11-03
Advisory published
2021-11-03
Advisory updated
2021-11-03

Who should care

Organizations that use Microsoft systems or components relying on the Enhanced Cryptographic Provider should prioritize this CVE, especially security teams responsible for patching, endpoint management, and vulnerability response. Any environment with internet-facing or high-value Windows assets should treat KEV-listed issues as urgent.

Technical summary

The vulnerability is described as a privilege escalation issue in Microsoft Enhanced Cryptographic Provider. CISA’s KEV entry identifies the affected vendor/project and directs organizations to apply updates per vendor instructions. No further technical mechanics are provided in the supplied corpus, so only the confirmed facts should be relied on: the CVE exists, it is KEV-listed, and remediation is required.

Defensive priority

High. KEV inclusion means this should move ahead of non-KEV vulnerabilities in normal patch queues, with remediation targeted no later than the KEV due date when possible.

Recommended defensive actions

  • Apply Microsoft updates per vendor instructions as soon as possible.
  • Verify whether any systems in your environment use or depend on the Enhanced Cryptographic Provider.
  • Prioritize remediation on internet-facing, privileged, and business-critical systems first.
  • Confirm patch deployment status and remove any exceptions or delays for this KEV item.
  • Monitor for signs of abuse on exposed or high-value endpoints until remediation is complete.

Evidence notes

The supplied source corpus includes CISA KEV metadata only. It confirms the CVE title, Microsoft as the vendor, the Enhanced Cryptographic Provider as the product, and the KEV dates: added 2021-11-03 and due 2021-11-17. The corpus also points to official CVE and NVD records, but no additional technical write-up was supplied here.

Sources and references

Verified primary and authoritative sources

  • CVE-2021-31199 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2021-31199

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2021-31199 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2021-31199

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.