Affects Microsoft SharePoint, a widely used enterprise platform; networked privilege escalation can enable admin takeover and broad disruption.
CVE-2026-123391
SharePoint authorization flaw lets authenticated users escalate privileges remotely.
Is CVE-2026-123391 being exploited?
Not confirmed. CVE-2026-123391 does not appear in CISA's Known Exploited Vulnerabilities catalog, which records only exploitation that has been observed and reported publicly. That is evidence of absence of a report, not evidence the flaw is unattacked. EPSS currently estimates a 0.80% probability of exploitation in the next 30 days.
How severe is CVE-2026-123391?
CVE-2026-123391 is rated High with a CVSS score of 8.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2026-123391?
Yes. A fix has been recorded for CVE-2026-123391. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-123391 affect?
CVE-2026-123391 affects Microsoft Office SharePoint, SharePoint Server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-123391?
Install Microsoft's security update immediately; review admin accounts and logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Authenticated attacker can elevate privileges on SharePoint remotely, potentially gaining admin rights, accessing sensitive data, and enabling lateral movement.
Immediate action required
- affected>= 16.0.0 and < 16.0.20326.20136
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
cisa ssvc
- exploitation
- none
- automatable
- no
- technical impact
- total
Assessed by CISA 11 Nov 2026 (SSVC 2.0.3).
timeline
- 10 Nov 2026Published
- 11 Nov 2026CISA SSVC assessment: exploitation none · same day later
- 11 Nov 2026CVE record last updated · same day later
- 11 Nov 2026Analysed by vulneraibility.com · same day later
- Patchmsrc.microsoft.com /update-guide/vulnerability/CVE-2026-123391
sources
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.