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CISA KEV · ACTIVELY EXPLOITED
HIGH severity

CVE-2019-9875

HIGH

CVE-2019-9875 is a high-severity (CVSS 8.8) Deserialization of Untrusted Data vulnerability. It is in CISA's Known Exploited Vulnerabilities catalog (added 2025-03-26) — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published
Updated
Affected
1 product
Patched
See advisory
Exploits
1 known
Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

  • Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2025-03-26. Federal agencies were required to remediate by 2025-04-16.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2019-9875.

EPSS Exploitation Probability

via FIRST.org ↗
13.8%probability of exploitation in next 30 days
Moderate Risk-0.25%
Lower risk than most CVEs97th percentile — riskier than 97% of all scored CVEsHighest risk
10.6%16.3%21.9%27.6%24.4%23.8%14.2%14.0%13.8%Apr 26Jul 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2019-9875 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 395,249 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Counts from FIRST.org, log-scaled.

Description

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.

Affected Products

1 product · 1 configurations
Application
cmssitecore
≤ 9.1
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Deserialization of Untrusted Data in the anti CSRF module in Sitecore th…

synacktiv.comNVDJun 2019

Detection & mitigation playbook

Vulnerability

  1. Detect

    Identify every host running the affected component and compare the installed build against the fixed version below — for source-built or distro-packaged software the version string, not a lockfile, is the source of truth (`dpkg -l`, `rpm -q`, or the binary's own `--version`).

  2. Remediation status

    No fixed release is recorded for CVE-2019-9875 yet. Track the upstream advisory, and apply the exposure-reduction steps below in the meantime.

  3. Mitigate without a patch

    Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

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.
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CVE-2019-9875: Deserialization (High 8.8, KEV)