Critical Deserialization RCE in Sitecore CMS & Experience Platform (CVE‑2019‑9875)
What It Is – Sitecore CMS and Experience Platform (XP) contain a deserialization flaw in the Sitecore.Security.AntiCSRF module. An authenticated attacker can supply a crafted .NET object in the __CSRFTOKEN POST parameter, leading to arbitrary code execution on the web server.
Exploitability – The vulnerability is publicly disclosed (CVE‑2019‑9875) and has a CVSS 3.1 base score of 9.8 (Critical). Exploits have been observed in the wild; mitigation requires applying Sitecore’s security update.
Affected Products – Sitecore CMS 9.x and Sitecore Experience Platform 9.x (any version that includes the vulnerable AntiCSRF component).
Why It Matters for Trust & Control Assurance
- Vulnerability Management – Demonstrates the need for continuous monitoring of third‑party software patches to satisfy the control objective of “maintain up‑to‑date, securely configured applications.”
- Audit Evidence – Timely remediation provides defensible evidence for auditors that the organization actively manages known risks.
- Supply‑Chain Assurance – Shows that relying on a CMS vendor does not eliminate the responsibility to verify that security updates are applied, a key trust signal for enterprise buyers.
Recommended Actions
- Inventory all Sitecore instances and verify version numbers.
- Apply Sitecore’s security patch for CVE‑2019‑9875 immediately.
- Conduct post‑patch testing to confirm the
__CSRFTOKENhandling is secure. - Update your vulnerability‑management workflow to flag any future Sitecore releases that address critical CVEs.
- Capture patch‑deployment evidence and map it to the relevant control objective in your framework of record.
Source: CISA KEV – CVE‑2019‑9875