CVE-2017-8540

The Microsoft Malware Protection Engine running on Microsoft Forefront and Microsoft Defender on Microsoft Windows Server 2008 SP2 and R2 SP1, Windows 7 SP1, Windows 8.1, Windows Server 2012 Gold and R2, Windows RT 8.1, Windows 10 Gold, 1511, 1607, and 1703, and Windows Server 2016, Microsoft Exchange Server 2013 and 2016, does not properly scan a specially crafted file leading to memory corruption. aka "Microsoft Malware Protection Engine Remote Code Execution Vulnerability", a different vulnerability than CVE-2017-8538 and CVE-2017-8541.

CVSS: 7.8Highscored by CISA
Exploited in the wild: Yes, in CISA KEV since 3 Mar 2022CISA deadline for US federal agencies: 24 Mar 2022public exploit code
EPSS: 71.9%chance of exploitation in the next 30 daystop 0.6% of scored CVEsFIRST score of 11 Nov 2026
Fix: Patch availablesee the advisories in the references
Published: 26 May 2017analysed here 12 Nov 2026

Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)

Summary

Triage

Attack surface: Server-side
Exploitable: At runtime
Attack vector: local
Weakness: CWE-787 Out-of-Bounds Write
Can a WAF block it?: No. See why

The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.

Affected products

Products named in our analysis

microsoft:malware_protection_engine
microsoft:endpoint_protection
microsoft:exchange_server
microsoft:forefront_endpoint_protection
microsoft:forefront_security
microsoft:intune_endpoint_protection
microsoft:security_essentials
microsoft:system_center_endpoint_protection
microsoft:windows_defender

Fix and mitigation

WAF and other mitigations

Can a WAF block it? No. The attack needs local access to the machine, so a WAF is not on its path.

Also consider: patch

Based on the attack vector (local or physical access). We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.

Remediation steps (AI-written)

Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.

Exploitation evidence

CISA KEV catalog: Listed since 3 Mar 2022.
CISA due date: 24 Mar 2022, the remediation deadline for US federal agencies
CISA required action: Apply updates per vendor instructions.
Public exploit code: Yes: 1 on Exploit-DB
CISA SSVC: exploitation active, automatable no, technical impact totalAssessed by CISA 10 Feb 2025 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.

Exploit-DB

Microsoft MsMpEng - Remote Use-After-Free Due to Design Issue in GC Enginedos, 30 May 2017, verified by Exploit-DB

Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.

Timeline

26 May 2017Published
30 May 2017First public exploit or proof of concept3 days later
3 Mar 2022Added to CISA KEV (exploited in the wild)1,738 days (about 5 years) later
24 Mar 2022CISA remediation due date (US federal agencies)21 days later
10 Feb 2025CISA SSVC assessment: exploitation active1,055 days (about 3 years) later
21 Oct 2025CVE record last updated253 days (about 8 months) later
12 Nov 2026Analysed by vulneraibility.com387 days (about 1 year) later

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Metric	Value	What it means
Attack vector	LocalLocal access required (shell, logged-in user).	Local access required (shell, logged-in user).
Attack complexity	LowRepeatable attack, no special conditions.	Repeatable attack, no special conditions.
Privileges required	NoneThe attacker needs no prior access.	The attacker needs no prior access.
User interaction	RequiredA victim must click, open or otherwise cooperate.	A victim must click, open or otherwise cooperate.
Scope	UnchangedImpact stays within the vulnerable component.	Impact stays within the vulnerable component.
Confidentiality	HighTotal data disclosure possible.	Total data disclosure possible.
Integrity	HighComplete modification possible.	Complete modification possible.
Availability	HighFull outage possible.	Full outage possible.

Common questions

Is CVE-2017-8540 being exploited?

Yes. CVE-2017-8540 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.

How severe is CVE-2017-8540?

CVE-2017-8540 is rated High with a CVSS score of 7.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.

Is there a patch for CVE-2017-8540?

Yes. A fix has been recorded for CVE-2017-8540. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.

What does CVE-2017-8540 affect?

CVE-2017-8540 affects microsoft:malware_protection_engine, microsoft:endpoint_protection, microsoft:exchange_server, microsoft:forefront_endpoint_protection, and 5 further products or versions. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.

Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.

References

NVD CVE.org CVE Details Source

5 references in the CVE record, grouped by the tags the record gives them.

Exploits (1)

exploit-db.com /exploits/42088/

Where the data on this page comes from

CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
NVD: CVSS and CPE data
CISA KEV catalog: exploitation, date added, due date
CISA Vulnrichment (ADP): SSVC decision points
FIRST EPSS: exploit probability and percentile
Exploit-DB: published exploits

Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.

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