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[NEW] [high] Microsoft Exchange Online: Vulnerability allows privilege escalation

highpublic exploitCVE-2026-54998
A remote, authenticated attacker can exploit a vulnerability in Microsoft Exchange Online to elevate their privileges.

CSIRTS triage

vendor: Microsoftproduct: Exchange OnlinePrivilege escalation
What
A remote, authenticated attacker can exploit a vulnerability in Microsoft Exchange Online to elevate their privileges.
Who is affected
Authenticated users of Microsoft Exchange Online are affected.
Urgency
Remediation is high urgency due to the potential for privilege escalation.
Action
Apply the latest security updates for Microsoft Exchange Online.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source
CERT-Bund (BSI) Security Advisories (DE · national-cert · site)
Severity
high
Published
2026-07-03
Exploitation
Not in CISA KEV at last sync
Language
Machine-translated to English — verify against the original

Original advisory: https://wid.cert-bund.de/portal/wid/securityadvisory?name=WID-SEC-2026-2191

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.

Referenced CVEs

CVECSIRTS overviewExternal
CVE-2026-54998coverage & exploitation statusNVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

Recent advisories for Microsoft Exchange Online

A cluster of recent advisories against the same product widens the attack surface — attackers routinely chain freshly published CVEs on one product, so review these together.

More from CERT-Bund (BSI) Security Advisories