Vulnary
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Critical· 9.8actively exploited

CVE-2026-58644

CVE-2026-58644 is a critical deserialization vulnerability in Microsoft SharePoint Server (2016/2019) allowing remote code execution via untrusted data. CISA mandates applying vendor mitigations or discontinuing use if mitigations are unavailable.

publishedJul 14, 2026
last modifiedJul 17, 2026
sourcesCISA-KEV · NVD
severity · cvss
9.8
critical · how bad it is
exploitation · epss
6%
93th percentile · chance of exploitation in 30 days
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →
auto-deletes from the system
counting…on Sep 1, 2026

No official fix yet. If none appears within 45 days of first tracking, this entry is removed automatically.

01

Who is affected

Microsoft SharePoint Server 2016 and 2019

02

Real-world impact

Known to be exploited (CISA KEV: YES)

03

Why this severity

CVSS 9.8 (critical): Remote code execution with high confidentiality, integrity, and availability impact

04

What to do about it

no official fix yet
recommended steps
  1. 01Apply mitigations per vendor instructions
  2. 02Follow CISA BOD 26-04 patching guidelines
  3. 03Discontinue use if mitigations are unavailable
interim mitigations
  • ›Ensure compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk
  • ›Evaluate asset internet exposure per CISA Forensics Triage Requirements

CISA KEV guidance and vendor advisories (no specific patch listed in sources)

05

Timeline

  1. Jul 14, 2026 · 19d ago
    Published
    Disclosed and added to the National Vulnerability Database.
  2. Jul 16, 2026 · 18d ago
    Confirmed exploited (CISA KEV)
    CISA added it to the Known Exploited Vulnerabilities catalog — attackers are using it in the wild.
  3. Jul 17, 2026 · 16d ago
    Advisory updated
    The NVD record was last revised.
  4. Jul 19, 2026 · 15d ago
    CISA remediation deadline
    Federal agencies are required to remediate by this date.
06

How it’s attacked

Attack vectorNetwork (remote)
Attack complexityLow
Privileges requiredNone
User interactionNone needed
ScopeUnchanged
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
07

References & advisories

NVD advisory ↗CISA KEV catalog ↗Search advisories ↗
(ai-assisted) A model wrote this summary from the official data, so double-check it against the source before you act on it. Read the official advisory →