Skip to main content
Varaxon Technologies

Known exploited vulnerability · CISA KEV

CVE-2026-58644: Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Microsoft SharePoint contains a deserialization of untrusted data vulnerability that allows an unauthorized attacker to execute code over a network.

CVE-2026-58644

Exploited in the wild. Fix this first.

CISA added it to the Known Exploited Vulnerabilities catalog on 2026-07-16: attackers are using it right now.

CISA KEV
Listed
Added 2026-07-16 · federal fix-by 2026-07-19
EPSS (30 days)
16%
Higher than 97% of CVEs · 2026-11-01
CVSS
No score

What CISA says

Microsoft SharePoint Deserialization of Untrusted Data Vulnerability

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Got a whole scan? Scan Hub runs this check on every finding in your Nessus, Qualys, Rapid7 or OpenVAS export and ranks the report by it.

Try it free

How to check if you are exposed to CVE-2026-58644

  1. Find every Microsoft SharePoint system you or your clients run, including ones exposed to the internet. Those come first: CISA only lists flaws attackers are already using.
  2. Compare each version with the fixed versions in the vendor advisory below. Where no fix exists yet, apply the vendor’s mitigation or take the system off the internet.
  3. Run a credentialed vulnerability scan to catch the systems you missed, then check that the next scan no longer reports CVE-2026-58644.

US federal agencies had to fix this by 2026-07-19. Everyone else should treat that deadline as a guide: if it has passed, this is overdue.

Timeline

  1. · Added to CISA's Known Exploited Vulnerabilities catalog
  2. · Fix-by date for US federal agencies, passed 105 days ago

Vendor advisories and fixes

Weakness type

More exploited Microsoft vulnerabilities

CISA lists 390 exploited Microsoft vulnerabilities. The closest matches:

Keep going

Sources: CISA Known Exploited Vulnerabilities catalog (version 2026.10.30); EPSS data from FIRST.org; CVSS and descriptions from the NIST National Vulnerability Database. Checked 2026-11-01. This product uses the NVD API but is not endorsed or certified by the NVD.

Cookie preferences

Essential site functions remain available whichever option you choose. Your advertising choice is saved on this site. The Scan Hub has a separate choice.

Google and Reddit may receive cookies, identifiers, browser and device information, and your network/IP information. Reject or withdraw at any time. Read the Privacy Policy.