CVE-2019-9875
Deserialization of Untrusted Data in the anti CSRF module in Sitecore through 9.1 allows an authenticated attacker to execute arbitrary code by sending a serialized .NET object in an HTTP POST parameter.
do firstApply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Can a WAF block it? Partly. The attack is delivered via an HTTP POST parameter containing a serialized .NET object, which is unusual but may resemble normal POST data. A WAF could partially detect this by matching serialized object patterns in POST parameters, but some legitimate requests might look similar. A custom WAF rule can filter HTTP POST parameter containing serialized .NET object, but attackers can vary the request. No tracked WAF vendor has published a rule for this CVE yet.
What a custom rule would match: HTTP POST parameter containing serialized .NET object
Also consider: patch · custom WAF rule · allow-list classes
Based on an AI reading of the CVE description, and no vendor rule found yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Is CVE-2019-9875 being exploited?
Yes. CVE-2019-9875 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2019-9875?
CVE-2019-9875 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2019-9875?
Yes. A fix has been recorded for CVE-2019-9875. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2019-9875 affect?
CVE-2019-9875 affects sitecore:cms. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
cisa ssvc
- exploitation
- active
- automatable
- no
- technical impact
- total
Assessed by CISA 26 Mar 2025 (SSVC 2.0.3).
timeline
- 31 May 2019Published
- 26 Mar 2025Added to CISA KEV (exploited in the wild) · 2,125 days (about 6 years) later
- 26 Mar 2025CISA SSVC assessment: exploitation active · 1 day later
- 16 Apr 2025CISA remediation due date (US federal agencies) · 20 days later
- 21 Oct 2025CVE record last updated · 189 days (about 6 months) later
- 2 Nov 2026Analysed by vulneraibility.com · 377 days (about 1 year) later
- Linkdev.sitecore.net /Downloads.aspx
- Linksynacktiv.com /blog.html
- Linksynacktiv.com /ressources/advisories/Sitecore_CSRF_deserialize_RCE.pdf
- Linkcisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-9875
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.