Affects Microsoft Exchange, a widely deployed enterprise mail server; remote code execution can disrupt orgs, compromise mailboxes, and enable domain-wide pivoting.
CVE-2026-70571
Remote code execution in Microsoft Exchange via stack-based buffer overflow.
Is CVE-2026-70571 being exploited?
Not confirmed. CVE-2026-70571 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 0.93% probability of exploitation in the next 30 days.
How severe is CVE-2026-70571?
CVE-2026-70571 is rated High with a CVSS score of 8.1. 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-2026-70571?
Yes. A fix has been recorded for CVE-2026-70571. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-70571 affect?
CVE-2026-70571 affects Microsoft Exchange Server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-70571?
Apply Exchange security update immediately; isolate exposed servers and monitor logs.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution on Exchange servers allowing arbitrary code execution, mailbox/data theft, and lateral movement.
Immediate action required
- affected>= 15.01.0.0 and < 15.01.2507.077
- affected>= 15.02.0.0 and < 15.02.1544.050
- affected>= 15.02.0.0 and < 15.02.1748.055
- affected>= 15.02.0.0 and < 15.02.2562.056
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.