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CVE-2025-53770

critical

Description

Deserialization of untrusted data in on-premises Microsoft SharePoint Server allows an unauthorized attacker to execute code over a network. Microsoft is aware that an exploit for CVE-2025-53770 exists in the wild. Microsoft is preparing and fully testing a comprehensive update to address this vulnerability. In the meantime, please make sure that the mitigation provided in this CVE documentation is in place so that you are protected from exploitation.

From the Tenable Blog

CVE-2025-53770: Frequently Asked Questions About Zero-Day SharePoint Vulnerability Exploitation
CVE-2025-53770: Frequently Asked Questions About Zero-Day SharePoint Vulnerability Exploitation

Published: 2025-07-20

Successful exploitation of CVE-2025-53770 could expose MachineKey configuration details from a vulnerable SharePoint Server, ultimately enabling unauthenticated remote code execution.

References

https://www.cisa.gov/news-events/alerts/2025/07/20/microsoft-releases-guidance-exploitation-sharepoint-vulnerability-cve-2025-53770

https://x.com/Shadowserver/status/1946900837306868163

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2025-53770

https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/echoes-in-the-shell-legacy-tooling-behind-ongoing-sharepoint-toolshell-exploitation/

https://www.theregister.com/2025/08/07/cisa_releases_malware_analysis/

https://www.bleepingcomputer.com/news/security/ransomware-gangs-join-attacks-targeting-microsoft-sharepoint-servers/

https://unit42.paloaltonetworks.com/microsoft-sharepoint-cve-2025-49704-cve-2025-49706-cve-2025-53770/

https://www.infosecurity-magazine.com/news/396-sharepoint-systems-compromised/

https://www.welivesecurity.com/en/eset-research/toolshell-an-all-you-can-eat-buffet-for-threat-actors/

https://www.securityweek.com/toolshell-attacks-hit-400-sharepoint-servers-us-government-victims-named/

https://www.darkreading.com/endpoint-security/ransomware-actors-toolshell-sharepoint-bugs

https://www.bleepingcomputer.com/news/security/microsoft-sharepoint-servers-also-targeted-in-ransomware-attacks/

https://cyberscoop.com/microsoft-sharepoint-attacks-400-victims-us-agencies/

https://www.bleepingcomputer.com/news/security/us-nuclear-weapons-agency-reportedly-hacked-in-sharepoint-attacks/

https://www.bleepingcomputer.com/news/security/us-nuclear-weapons-agency-hacked-in-microsoft-sharepoint-attacks/

https://securityaffairs.com/180267/apt/microsoft-linked-attacks-on-sharepoint-flaws-to-china-nexus-actors.html

https://arstechnica.com/security/2025/07/what-to-know-about-toolshell-the-sharepoint-threat-under-mass-exploitation/

https://www.securityweek.com/toolshell-zero-day-attacks-on-sharepoint-first-wave-linked-to-china-hit-high-value-targets/

https://www.securityweek.com/microsoft-says-chinese-apts-exploited-toolshell-zero-days-weeks-before-patch/

https://www.microsoft.com/en-us/security/blog/2025/07/22/disrupting-active-exploitation-of-on-premises-sharepoint-vulnerabilities/

https://www.infosecurity-magazine.com/news/sharepoint-toolshell-chinese/

https://www.darkreading.com/application-security/3-china-nation-state-actors-sharepoint-bugs

https://www.axios.com/2025/07/22/microsoft-sharepoint-china-hack-targets

https://therecord.media/microsoft-sharepoint-vulnerabilities-china-groups-exploiting

https://thehackernews.com/2025/07/microsoft-links-ongoing-sharepoint.html

https://thehackernews.com/2025/07/hackers-exploit-sharepoint-zero-day.html

https://thehackernews.com/2025/07/cisa-orders-urgent-patching-after.html

https://securityaffairs.com/180252/hacking/sharepoint-under-fire-new-toolshell-attacks-target-enterprises.html

https://hackread.com/microsoft-chinese-state-hackers-exploit-sharepoint-flaws/

https://cyberscoop.com/microsoft-sharepoint-zero-days-china-typhoon/

https://www.theregister.com/2025/07/21/massive_security_snafu_microsoft/

https://www.security.com/threat-intelligence/toolshell-zero-day-sharepoint-cve-2025-53770

https://www.infosecurity-magazine.com/news/microsoft-compromising-sharepoint/

https://www.hipaajournal.com/microsof-emergency-patches-sharepoint-server-vulnerabilities/

https://www.databreachtoday.com/attackers-exploit-zero-day-flaws-in-on-premises-sharepoint-a-29018

https://www.darkreading.com/remote-workforce/microsoft-rushes-emergency-fix-exploited-sharepoint-toolshell-flaw

https://therecord.media/microsoft-sharepoint-zero-day-vulnerability-exploited-globally

https://securityaffairs.com/180211/hacking/u-s-cisa-urges-to-immediately-patch-microsoft-sharepoint-flaw-adding-it-to-its-known-exploited-vulnerabilities-catalog.html

https://krebsonsecurity.com/2025/07/microsoft-fix-targets-attacks-on-sharepoint-zero-day/

https://hackread.com/microsoft-hackers-exploit-sharepoint-flaws-patch-now/

https://cyberscoop.com/microsoft-sharepoint-zero-day-attack-spree/

https://blog.talosintelligence.com/toolshell-affecting-sharepoint-servers/

https://blog.checkpoint.com/research/sharepoint-zero-day-cve-2025-53770-actively-exploited-what-security-teams-need-to-know/

https://arstechnica.com/security/2025/07/sharepoint-vulnerability-with-9-8-severity-rating-is-under-exploit-across-the-globe/

https://www.securityweek.com/sharepoint-under-attack-microsoft-warns-of-zero-day-exploited-in-the-wild-no-patch-available/

https://www.cisa.gov/news-events/alerts/2025/07/20/cisa-adds-one-known-exploited-vulnerability-cve-2025-53770-toolshell-catalog

https://www.bleepingcomputer.com/news/microsoft/microsoft-sharepoint-zero-day-exploited-in-rce-attacks-no-patch-available/

https://thehackernews.com/2025/07/microsoft-releases-urgent-patch-for.html

https://thehackernews.com/2025/07/critical-microsoft-sharepoint-flaw.html

https://isc.sans.edu/diary/rss/32122

https://go.theregister.com/feed/www.theregister.com/2025/07/21/infosec_in_brief/

https://research.eye.security/sharepoint-under-siege/

https://msrc.microsoft.com/blog/2025/07/customer-guidance-for-sharepoint-vulnerability-cve-2025-53770/

https://securelist.com/toolshell-explained/117045/

https://www.theregister.com/2025/07/24/microsoft_sharepoint_ransomware/

https://www.theregister.com/2025/07/22/microsoft_sharepoint_2016_patch/

https://go.theregister.com/feed/www.theregister.com/2025/07/22/microsoft_sharepoint_2016_patch/

https://www.tenable.com/blog/cve-2025-53770-frequently-asked-questions-about-zero-day-sharepoint-vulnerability-exploitation

https://www.forbes.com/sites/daveywinder/2025/07/20/microsoft-confirms-ongoing-mass-sharepoint-attack---no-patch-available/

https://news.ycombinator.com/item?id=44629710

Details

Source: Mitre, NVD

Published: 2025-07-20

Updated: 2025-07-30

Named Vulnerability: ToolShellKnown Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 10

Vector: CVSS2#AV:N/AC:L/Au:N/C:C/I:C/A:C

Severity: Critical

CVSS v3

Base Score: 9.8

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

Severity: Critical

EPSS

EPSS: 0.69382

Vulnerability Watch

Tenable Research has classified this CVE under the following Vulnerability Watch classification, which includes active and historical (inactive) classifications. You can learn more about these classifications on our blog.

Vulnerability of Concern