Affects Microsoft Exchange Server — widely deployed enterprise mail server; network-level privilege escalation could cause broad data and admin compromise.
CVE-2026-62911
Authentication bypass via replay in Microsoft Exchange enabling privilege escalation
Is CVE-2026-62911 being exploited?
Not confirmed. CVE-2026-62911 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 1.3% probability of exploitation in the next 30 days.
How severe is CVE-2026-62911?
CVE-2026-62911 is rated High with a CVSS score of 8.0. 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-2026-62911?
Yes. A fix has been recorded for CVE-2026-62911. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-62911 affect?
CVE-2026-62911 affects Microsoft Exchange Server (on-premises). Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-62911?
Apply vendor patch ASAP; if unavailable, restrict Exchange network access and enable enhanced logging
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Capture-replay authentication bypass allows elevation of privileges on Exchange over the network, enabling mailbox access, data modification, or admin takeover.
Immediate action required
- affected>= 15.01.0.0 and < 15.01.2507.072
- affected>= 15.02.0.0 and < 15.02.1544.044
- affected>= 15.02.0.0 and < 15.02.1748.049
- affected>= 15.02.0.0 and < 15.02.2562.046
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.