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PatchSiren cyber security CVE debrief

CVE-2019-9875 Sitecore CVE debrief

CVE-2019-9875 is a deserialization vulnerability affecting Sitecore CMS and Experience Platform (XP). CISA added it to the Known Exploited Vulnerabilities catalog on 2025-03-26, which means it should be treated as an actively exploited issue rather than a theoretical one. The source corpus does not provide deeper technical impact details, so the safest interpretation is to prioritize remediation using vendor guidance and KEV-directed defensive actions.

Vendor
Sitecore
Product
CMS and Experience Platform (XP)
CVSS
Unknown
CISA KEV
Listed
Original CVE published
2025-03-26
Original CVE updated
2025-03-26
Advisory published
2025-03-26
Advisory updated
2025-03-26

Who should care

Organizations running Sitecore CMS or Sitecore Experience Platform (XP), especially internet-facing deployments, shared-hosting environments, and teams responsible for application security, patching, and platform operations. Security teams should also care because KEV inclusion creates a time-bound remediation requirement.

Technical summary

The available source data identifies the flaw as a deserialization vulnerability in Sitecore CMS and Experience Platform (XP). CISA’s KEV listing confirms known exploitation, but the provided corpus does not include the exploit mechanics, attack prerequisites, or downstream effects. From a defensive standpoint, the key takeaway is that unsafe deserialization issues can be high-risk and should be handled as urgent when flagged as known exploited.

Defensive priority

High. KEV inclusion indicates confirmed exploitation and a short remediation window. If Sitecore guidance does not provide a workable mitigation path, CISA’s note instructs organizations to discontinue use of the product until a safe remediation path is available.

Recommended defensive actions

  • Apply mitigations per Sitecore vendor instructions referenced by CISA.
  • Prioritize affected Sitecore CMS and XP instances for immediate inventory and exposure review.
  • If mitigations are unavailable or cannot be safely applied, discontinue use of the product in line with CISA guidance.
  • Follow applicable BOD 22-01 guidance for cloud services where relevant.
  • Validate remediation by confirming the vulnerable Sitecore deployment is no longer reachable in an exploitable state.
  • Track this CVE as a KEV-driven SLA item with the CISA due date of 2025-04-16.

Evidence notes

CISA’s KEV metadata identifies the issue as “Sitecore CMS and Experience Platform (XP) Deserialization Vulnerability,” with dateAdded 2025-03-26 and dueDate 2025-04-16, and notes to apply vendor mitigations or discontinue use if mitigations are unavailable. The source metadata also references Sitecore KB0038556 and the NVD detail page. The provided corpus does not include additional vendor advisory text or exploit details, so this debrief avoids unsupported claims.

Sources and references

Verified primary and authoritative sources

  • CVE-2019-9875 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2019-9875

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2019-9875 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2019-9875

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

  • CISA Known Exploited Vulnerabilities catalog

    Publisher, destination, and source semantics verified

    URL: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

    Cybersecurity and Infrastructure Security Agency - Official CISA catalog of vulnerabilities known to be exploited in the wild.

Supplemental references

  • Source item URL

    Unverified legacy reference

    URL: https://www.cisa.gov/sites/default/files/feeds/known_exploited_vulnerabilities.json

    cisa_kev

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.