CVE-2026-58644: Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
Actively exploited. At least one CVE in this advisory is listed in the CISA Known Exploited Vulnerabilities catalog — exploitation has been observed in the wild. Treat remediation as urgent.
Deserialization of untrusted data in Microsoft Office SharePoint allows an unauthorized attacker to execute code over a network.
CSIRTS triage
- What
- Deserialization of untrusted data allows unauthorized code execution over a network.
- Who is affected
- Users of Microsoft Office SharePoint.
- Urgency
- Critical urgency due to confirmed exploitation and high severity.
- Action
- Apply the necessary updates immediately.
AI-assisted analysis generated from the source advisory — verify against the original.
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Details
Original advisory: https://nvd.nist.gov/vuln/detail/CVE-2026-58644
Exploitation outlook
EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.
- Exploitation confirmedCVE-2026-58644Already exploited in the wild (CISA KEV) — the prediction phase is over. Patch now. Riskier than 93% of all scored CVEs.
Referenced CVEs
| CVE | CSIRTS overview | External |
|---|---|---|
| CVE-2026-58644 | coverage & exploitation status | NVD · CVE.org |
Same CVEs, other sources
How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.
- unknownexploitedSecurity Alert: [Updated] Microsoft Releases July 2026 Security Updatesjpcert
- criticalexploitedMicrosoft security advisory – July 2026 monthly rollup (AV26-698) – Update 3cccs
- criticalexploited2026-009: Critical Vulnerabilities in Microsoft SharePointcert-eu
- unknownexploitedMultiple vulnerabilities in Microsoft Sharepoint (July 22, 2026)cert-fr-alerte
- unknownexploitedNCSC-2026-0237 [1.02] [H/H] Vulnerabilities Fixed in Microsoft Officencsc-nl
- unknownexploitedNCSC-2026-0237 [1.01] [H/H] Vulnerabilities fixed in Microsoft Officencsc-nl
- highexploitedCISA Adds Three Known Exploited Vulnerabilities to Catalogcisa
- criticalexploitedCVE-2026-58644: Microsoft SharePoint Deserialization of Untrusted Data Vulnerabilitycisa-kev
- criticalexploitedAL26-017 - Critical vulnerabilities impacting Microsoft SharePoint Server – CVE-2026-56164, CVE-2026-55040 and…cccs
- unknownexploitedNCSC-2026-0237 [1.00] [M/H] Vulnerabilities fixed in Microsoft Officencsc-nl
- unknownexploitedCISA Urges SharePoint Hardening After New Exploitationscisa
- criticalexploitedCVE-2026-58644: Microsoft SharePoint Remote Code Execution Vulnerabilitymsrc