CVE-2026-50873
Arbitrary file upload in flatnotes 5.5.4 enables RCE.
Is CVE-2026-50873 being exploited?
Not confirmed. CVE-2026-50873 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-2026-50873?
CVE-2026-50873 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-2026-50873?
Not known from our data. No patch reference has been recorded for CVE-2026-50873, which is not the same as no patch existing — a fix may have shipped without a tagged reference, or after this record was written. The vendor advisory is the only authority on whether a fix exists, and mitigations may be available regardless.
What does CVE-2026-50873 affect?
CVE-2026-50873 affects flatnotes v5.5.4. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-50873?
Patch when released; validate uploads and sandbox attachments.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
RCE via crafted HTML/SVG upload; attacker can run code on target host.
Immediate action required