Sitecore flaws being used in attacks

CISA lists 4 flaws in Sitecore products as being used in attacks, most recently on 4 Sep 2025. 1 has been used in ransomware.

What to do

1. Update every Sitecore product you use.Install the updates Sitecore offers, on every device, and restart when asked. Each flaw below has a fix or clear advice; that’s one of CISA’s conditions for listing it.
2. If someone looks after IT for you, send them this page.Many of these are in equipment you don’t see: routers, firewalls, servers, the office network. Ask them to confirm each one is fixed, or that you don’t use the product.
3. Check anything else in the lookup.Search any app, company or CVE. Not being on CISA’s list doesn’t mean safe: keep updating either way.

Every flaw, newest first

1. Being used in attacksAdded by CISA on 4 Sep 2025
   Sitecore Multiple Products
   CVE-2025-53690Sitecore Multiple Products Deserialization of Untrusted Data Vulnerability
   Sitecore Experience Manager (XM), Experience Platform (XP), Experience Commerce (XC), and Managed Cloud contain a deserialization of untrusted data vulnerability involving the use of default machine keys. This flaw allows attackers to exploit exposed ASP.NET machine keys to achieve remote code execution.
   CISA’s required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
2. Being used in attacksAdded by CISA on 26 Mar 2025
   Sitecore CMS and Experience Platform (XP)
   CVE-2019-9875Sitecore CMS and Experience Platform (XP) Deserialization Vulnerability
   Sitecore CMS and Experience Platform (XP) contain a deserialization vulnerability in the Sitecore.Security.AntiCSRF module that allows an authenticated attacker to execute arbitrary code by sending a serialized .NET object in the HTTP POST parameter __CSRFTOKEN.
   CISA’s required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
3. Being used in attacksAdded by CISA on 26 Mar 2025
   Sitecore CMS and Experience Platform (XP)
   CVE-2019-9874Sitecore CMS and Experience Platform (XP) Deserialization Vulnerability
   Sitecore CMS and Experience Platform (XP) contain a deserialization vulnerability in the Sitecore.Security.AntiCSRF module that allows an unauthenticated attacker to execute arbitrary code by sending a serialized .NET object in the HTTP POST parameter __CSRFTOKEN.
   CISA’s required actionApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
   CVE recordNVD
4. Being used in attacksUsed in ransomwareAdded by CISA on 25 Mar 2022
   Sitecore XP
   CVE-2021-42237Sitecore XP Remote Command Execution Vulnerability
   Sitcore XP contains an insecure deserialization vulnerability which can allow for remote code execution.
   CISA’s required actionApply updates per vendor instructions.
   CVE recordNVD

From CISA’s Known Exploited Vulnerabilities catalog, updated 21 Oct 2026 (version 2026.10.21). CISA’s required actions are written for US government agencies. Sitecore on CISA’s site.