CVE-2026-103646
Unauthenticated account takeover in Ultimate Multisite WordPress plugin
Is CVE-2026-103646 being exploited?
Not confirmed. CVE-2026-103646 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 0.44% probability of exploitation in the next 30 days.
How severe is CVE-2026-103646?
CVE-2026-103646 is rated Critical with a CVSS score of 9.8. 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-2026-103646?
Yes. A fix has been recorded for CVE-2026-103646. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-103646 affect?
CVE-2026-103646 affects Ultimate Multisite WordPress plugin <= 2.16.1, WordPress Multisite sites using the plugin. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-103646?
Upgrade to Ultimate Multisite 2.17.0 immediately; reset admin passwords and audit logins
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attacker can log in as any existing user—including Network Super Admin—by linking a checkout to a target email (auth bypass).
Immediate action required
- affected< 2.17.0
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.