CVE-2026-41259
Mastodon email validation bypass may lead to RCE.
Is CVE-2026-41259 being exploited?
Not confirmed. CVE-2026-41259 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 0.21% probability of exploitation in the next 30 days.
How severe is CVE-2026-41259?
CVE-2026-41259 is rated High with a CVSS score of 8.2. 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-2026-41259?
Yes. A fix has been recorded for CVE-2026-41259. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-41259 affect?
CVE-2026-41259 affects Mastodon server (self-hosted) < v4.5.9, < v4.4.16, < v4.3.22. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-41259?
Upgrade to patched versions (>=4.5.9 or 4.4.16/4.3.22).
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote code execution via crafted email parsing in sign-up flow; could compromise server.
Immediate action required
- affected< 4.3.22
- affected>= 4.4.0-beta.1 and < 4.4.16
- affected>= 4.5.0-beta.1 and < 4.5.9
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.