# ToolShell: mass exploitation of on-prem SharePoint (CVE-2025-53770, CVE-2025-49704, CVE-2025-49706) · pwn.watch

> Unauthenticated RCE chain against on-premises SharePoint Server, mass-exploited from July 18, 2025. Microsoft observed Linen Typhoon, Violet Typhoon and Storm-2603 exploiting it; Storm-2603 deployed Warlock ransomware. Patching alone is not enough: rotate ASP.NET machine keys and restart IIS. SharePoint Online was not affected.

Page: https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770 · generated 2026-10-23T01:56:39.502Z

## Status
- Severity: critical · status: closed · patch: patched
- Product: Microsoft SharePoint Server (on-premises)
- Started: 2025-07-18 · closed: 2025-07-22
- CVEs: CVE-2025-49704, CVE-2025-49706, CVE-2025-53770
- Affected: On-premises SharePoint Server (see Microsoft customer guidance for the exact builds)
- Fixed in: See Microsoft customer guidance for CVE-2025-53770

## Follow this incident
- RSS (one item per update): https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770/feed.xml
- JSON Feed: https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770/feed.json
- Full data (timeline, sources, posts, agentBrief): https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770.json
- This file: https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770/llms.txt

## Updates (newest first)
- 2025-07-22: Microsoft attributes exploitation to Linen Typhoon, Violet Typhoon and Storm-2603 (https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/)
- 2025-07-22: CISA adds CVE-2025-49704 and CVE-2025-49706 to KEV
- 2025-07-20: CISA adds CVE-2025-53770 to KEV and publishes guidance (https://www.cisa.gov/news-events/alerts/2025/07/20/update-microsoft-releases-guidance-exploitation-sharepoint-vulnerabilities)
- 2025-07-19: Microsoft publishes customer guidance for CVE-2025-53770 (https://www.microsoft.com/en-us/msrc/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770)
- 2025-07-18: Eye Security observes large-scale exploitation of on-prem SharePoint servers (https://research.eye.security/sharepoint-under-siege/)

## Fix brief
# Security brief: ToolShell: mass exploitation of on-prem SharePoint (CVE-2025-53770, CVE-2025-49704, CVE-2025-49706)

Source: https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770 · status: closed (closed Jul 22, 2025) · severity: critical · updated Jul 22, 2025

## Patch status
**PATCHED: fixed releases exist. Upgrade to a fixed version.**

## What it is
Unauthenticated RCE chain against on-premises SharePoint Server, mass-exploited from July 18, 2025. Microsoft observed Linen Typhoon, Violet Typhoon and Storm-2603 exploiting it; Storm-2603 deployed Warlock ransomware. Patching alone is not enough: rotate ASP.NET machine keys and restart IIS. SharePoint Online was not affected.

Severity detail: Unauthenticated RCE chain; mass exploitation; CISA KEV; known ransomware use (Warlock)

- Product: Microsoft SharePoint Server (on-premises)
- CVE / advisory ids: CVE-2025-49704, CVE-2025-49706, CVE-2025-53770

## Affected versions
- On-premises SharePoint Server (see Microsoft customer guidance for the exact builds)

## Check whether you're affected
No generic command applies (the product is a hosted service, appliance or desktop app). Check the installed version in its admin UI / About screen and compare with the versions above.

## Fix
Upgrade to one of these fixed versions (or later on the same branch):
- See Microsoft customer guidance for CVE-2025-53770

After upgrading, re-run the checks above and redeploy/restart the affected services.

## Latest updates
- Jul 22, 2025: Microsoft attributes exploitation to Linen Typhoon, Violet Typhoon and Storm-2603
- Jul 22, 2025: CISA adds CVE-2025-49704 and CVE-2025-49706 to KEV
- Jul 20, 2025: CISA adds CVE-2025-53770 to KEV and publishes guidance
- Jul 19, 2025: Microsoft publishes customer guidance for CVE-2025-53770
- Jul 18, 2025: Eye Security observes large-scale exploitation of on-prem SharePoint servers

## Advisories
- [Customer guidance for SharePoint vulnerability CVE-2025-53770](https://www.microsoft.com/en-us/msrc/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770) (Microsoft)
- [UPDATE: Microsoft Releases Guidance on Exploitation of SharePoint Vulnerabilities](https://www.cisa.gov/news-events/alerts/2025/07/20/update-microsoft-releases-guidance-exploitation-sharepoint-vulnerabilities) (CISA)
- [Joint Statement on SharePoint vulnerabilities](https://www.enisa.europa.eu/news/joint-statement-on-sharepoint-vulnerabilities-assessment-and-advice-on-recovery-and-mitigating-actions) (ENISA)
- [NVD: CVE-2025-53770](https://nvd.nist.gov/vuln/detail/CVE-2025-53770) (NVD)
- [NVD: CVE-2025-49704](https://nvd.nist.gov/vuln/detail/CVE-2025-49704) (NVD)
- [NVD: CVE-2025-49706](https://nvd.nist.gov/vuln/detail/CVE-2025-49706) (NVD)
- [CISA Known Exploited Vulnerabilities Catalog](https://www.cisa.gov/known-exploited-vulnerabilities-catalog) (CISA)

## Write-ups & news
- [Disrupting active exploitation of on-premises SharePoint vulnerabilities](https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/)
- [SharePoint Under Siege: ToolShell Exploit](https://research.eye.security/sharepoint-under-siege/)

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Machine-readable: https://pwn.watch/i/toolshell-sharepoint-cve-2025-53770.json · all incidents: https://pwn.watch/incidents.json. Verify against the vendor advisory before changing production systems.