Vulnerability report

Active exploitation observed Confirmed confidence In CISA KEV

CVE-2026-65660

Microsoft SharePoint Server Remote Code Execution Vulnerability

Microsoft SharePoint Enterprise Server 2016 · affected before 16.0.5565.1001

Watch CVE-2026-65660 Browse KEV feed
Severity
CVSS 8.8 · High
Confidence
Confirmed
Exploit status
Observed in sensors
EPSS
2.1%
First observed
24 Sep 2026
Last observed
30 Sep 2026

Decision summary

What security teams need to know first

Direct answers before the deeper technical record.

What it is

CVE-2026-65660 is Microsoft SharePoint Server Remote Code Execution Vulnerability. Improper control of generation of code ('code injection') in Microsoft Office SharePoint allows an authorized attacker to execute code...

Is it exploited?

Yes. Previdian sensors observed exploitation attempts with confirmed confidence. Listed in CISA KEV. Also confirmed by third-party sources.

Who is affected?

Microsoft SharePoint Enterprise Server 2016 affected before 16.0.5565.1001.

What should we do?

Patch immediately, validate internet-facing exposure, and monitor for matching requests.

Overview

Microsoft SharePoint Server Remote Code Execution Vulnerability

Improper control of generation of code ('code injection') in Microsoft Office SharePoint allows an authorized attacker to execute code over a network.

Microsoft Affected
Microsoft SharePoint Enterprise Server 2016
Before 16.0.5565.1001
Microsoft Affected
Microsoft SharePoint Server 2019
Before 16.0.10417.20198
Microsoft Affected
Microsoft SharePoint Server Subscription Edition
Before 16.0.19725.20522
View vendor advisory (opens in new tab)
Published
11 Aug 2026
Exploitation Reported
24 Sep 2026
Attack vector
Remote
Complexity
Low
Privileges
Low
User interaction
None

Tags

microsoft cisa

CVE References

Exploitation evidence

Why Previdian marks this CVE as exploited

Third-party attestation and first-party sensor observation are shown separately so teams can judge the evidence chain.

Exploited in the wild

Previdian

Recorded 24 Sep 2026

Previdian independently recorded this as exploited after first seeing it in honeypot sensors.

Active exploitation observed

Previdian sensor

First observed 24 Sep 2026

Previdian first observed exploitation attempts targeting this vulnerability in our honeypot sensors.

Proof of concept available

Recorded 22 Sep 2026

Public scanner or PoC coverage increases practical exploitability.

Known exploited vulnerability sources

Per-source evidence links for KEV attestations are available through the Previdian Pro API.

Learn about Pro API access
Source Added
Previdian Sensors First 2026-09-24 12:32 UTC
CISA 2026-09-25 15:11 UTC
CVE 2026-09-25 15:50 UTC
Security Affairs 2026-09-25 22:21 UTC
The Hacker News 2026-09-26 09:30 UTC

Operational indicators for this CVE are listed under Detection.

Sensor telemetry

First-party evidence of exploitation activity

Previdian sensors recorded exploitation attempts targeting this vulnerability. The cards and chart show volume, unique attackers, and daily activity.

20

Attempts observed

5

Unique attacker IPs

3

Attacker countries

GB · IL · US

1

Sensors observed

CVE-2026-65660 exploitation attempts over the last 18 days

Daily events observed by Previdian sensors

Updated 10 Oct 2026

0
16
0
0
0
2
1
1
0
0
0
0
0
0
0
0
0
0
23 Sep 27 Sep 1 Oct 5 Oct 10 Oct

First observed 24 Sep 2026 · Last observed 30 Sep 2026

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Detection

Operational artifacts and observed signals

Make the evidence actionable in scanner, SOC, and edge-control workflows.

Observed signals

Request targets
User-Agents
Callback hosts
9
2
0

Request targets and User-Agents available in Pro. Callback host details available in Enterprise.

Scanner coverage

No scanner integrations recorded yet.

Virtual patch status

Previdian virtual patch guidance is available for this CVE.

AWS WAF Cloudflare ModSecurity

Attacker IP Indicators

Attacker IP indicators observed · available in Pro and Enterprise.

Sensor-derived attacker IP indicators are available to Pro and Enterprise accounts under Detection and through the Pro API.

Learn about Pro API access

Virtual Patch Detail

Compensating WAF rules for this CVE.

Available

Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to Previdian Enterprise users.

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Risk and context

Severity, weaknesses, and research context

CVSS v3.1

8.8 High

Potential damage if exploited. Separate from whether attackers are using it.

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

EPSS

2.1%

Estimated chance of exploitation in the next 30 days. Previdian's warning comes from evidence, not this score.

Weaknesses

Improper Control of Generation of Code ('Code Injection') CWE-94

Recent mention · The Hacker News

SharePoint RCE and MikroTik RouterOS Flaws Actively Exploited in the Wild

Ravie LakshmananSep 26, 2026Vulnerability / Network Security The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added two security flaws impacting Microsoft SharePoint and Mikrotik RouterOS to its Known Exploited Vulnerabilities (KEV) catalog, citing...

Read full advisory

All Mentions

Recent mention · The Hacker News

SharePoint RCE and MikroTik RouterOS Flaws Actively Exploited in the Wild

The Hacker News · 26 Sep 2026

Ravie LakshmananSep 26, 2026Vulnerability / Network Security The U.S. Cybersecurity and Infrastructure Security Agency (CISA) on Friday added two security flaws impacting Microsoft SharePoint and Mikrotik RouterOS to its Known Exploited Vulnerabilities (KEV) catalog, citing evidence of active exploitation. The vulnerabilities in question are as follows - CVE-2026-65660 (CVSS score: 8.8) - A code injection vulnerability in Microsoft Office SharePoint that allows an authorized attacker to execute code over a network. CVE-2026-67279 (CVSS score: 6.9) - An improper enforcement of behavioral...

Recent mention · Security Affairs

U.S. CISA adds Microsoft SharePoint and Mikrotik RouterOS flaws to its Known Exploited Vulnerabilities catalog

Security Affairs · 25 Sep 2026

U.S. Cybersecurity and Infrastructure Security Agency (CISA) adds Microsoft SharePoint and Mikrotik RouterOS flaws flaws to its Known Exploited Vulnerabilities catalog. The U.S. Cybersecurity and Infrastructure Security Agency (CISA) added the following vulnerabilities to its Known Exploited Vulnerabilities (KEV) catalog: CVE-2026-65660 is a code-injection vulnerability in Microsoft SharePoint Server that allows an authenticated, low-privileged attacker to execute arbitrary […]

Recent mention · The Hacker News

SharePoint Flaw Initially Listed as Spoofing by Microsoft Enables Authenticated RCE

The Hacker News · 22 Sep 2026

Swati KhandelwalSep 22, 2026Vulnerability / Web Security A SharePoint Server vulnerability that Microsoft initially classified as a spoofing flaw with a CVSS score of 6.5 actually enables authenticated remote code execution, according to full technical details published today by Viettel Cyber Security researcher Dinh Ho Anh Khoa. The flaw, CVE-2026-65660, affects SharePoint Server 2016, 2019, and Subscription Edition. Patches have been available since the August 11 security updates, and the National Vulnerability Database scores it 8.8. Microsoft's advisory describes CVE-2026-65660 as...

Recent mention · Rapid7

Patch Tuesday - August 2026

Rapid7 · 11 Aug 2026

Microsoft is publishing 421 vulnerabilities on August 2026 Patch Tuesday, including 236 vulnerabilities in Windows. This is lower volume than last month’s record-breaking behemoth, but still one of the largest Patch Tuesday totals ever. There is no reason to suppose that Patch Tuesday will ever return to the lower volumes we saw prior to 2026. Microsoft is aware of exploitation in the wild for one of the vulnerabilities published today, as well as public disclosure for two others, although the Notable CVEs section of the Security Update Guide omits one of these. As usual, browser vulns are...

Recent mention · Tenable Blog

Microsoft's August 2026 Patch Tuesday addresses 398 CVEs (CVE-2026-68820)

Tenable Blog · 11 Aug 2026

42Critical355Important1Moderate0LowMicrosoft addresses 398 CVEs in the eighth Patch Tuesday of 2026, with three zero-days, including one that was exploited in the wild.Microsoft patched 398 CVEs in its August 2026 Patch Tuesday release, with 42 rated critical, 355 rated as important and one rated as moderate. Our counts omitted two CVEs assigned by MITRE; CVE-2026-6726 and CVE-2026-6727.This month’s update includes patches for:.NET.NET Core.NET FrameworkAMD ZenActive Directory Certificate Services (AD CS)Application Information ServicesAzure Active DirectoryAzure CycleCloudAzure Monitor...

Recent mention · Tenable Blog

Microsoft's August 2026 Patch Tuesday Addresses 398 CVEs (CVE-2026-68820)

Tenable Blog · 11 Aug 2026

42Critical355Important1Moderate0LowMicrosoft addresses 398 CVEs in the eighth Patch Tuesday of 2026, with three zero-days, including one that was exploited in the wild.Microsoft patched 398 CVEs in its August 2026 Patch Tuesday release, with 42 rated critical, 355 rated as important and one rated as moderate. Our counts omitted two CVEs assigned by MITRE; CVE-2026-6726 and CVE-2026-6727.This month’s update includes patches for:.NET.NET Core.NET FrameworkAMD ZenActive Directory Certificate Services (AD CS)Application Information ServicesAzure Active DirectoryAzure CycleCloudAzure Monitor...

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

SharePoint CVE-2026-65660: From Anonymous Access to Pre-Auth RCE via EditingPageParser Type-Check Bypass

public · Created 2026-09-22 00:00:00 UTC

Timeline

From disclosure to observed exploitation

  1. 13:44 UTC

    Virtual patch available

    Compensating WAF rule available to block exploitation

  2. 09:30 UTC

    KEV confirmed by The Hacker News

    Exploitation attested by an external source

  3. 22:21 UTC

    KEV confirmed by Security Affairs

    Exploitation attested by an external source

  4. 15:50 UTC

    KEV confirmed by CVE

    Exploitation attested by an external source

  5. 15:11 UTC

    Added to CISA KEV

    Listed in the CISA Known Exploited Vulnerabilities catalog

  6. 12:05 UTC

    Indicators of compromise added (5)

    Indicators of compromise recorded

  7. 12:05 UTC

    Observed by Previdian sensors

    Evidence-backed exploitation signal

  8. 11:22 UTC

    Added to the Previdian watchlist

    Pro and Enterprise Watch users had 3 days of early warning before CISA KEV. Also 2 days before Previdian confirmed it as a KEV.

  9. 00:00 UTC

    Public PoC available

    Public proof-of-concept code published

  10. 17:04 UTC

    CVE published

    Vulnerability disclosed publicly

  11. 18:16 UTC

    CVE ID reserved

    Identifier reserved by the CNA

Pro API

Automate this intelligence

Confidence, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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  • Evidence confidence and provenance
  • First-party sensor telemetry
  • PoC and scanner references
  • Affected versions and enrichment
  • Automation-ready JSON delivery

GET /api/v2/pro/kevs/CVE-2026-65660

Free JSON includes basic KEV fields 
{
  "cve_id": "CVE-2026-65660",
  "confidence": "Confirmed",
  "cvss_score": 8.8,
  "cvss_estimated": false,
  "epss_score": 0.02101,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": true
  },
  "sensor_telemetry": { "attempts": 20, "sensors": 1 }
}