CVE-2026-27124
Auth bypass in FastMCP OAuthProxy via GitHub consent bypass (pre-3.2.0)
Is CVE-2026-27124 being exploited?
Not confirmed. CVE-2026-27124 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-2026-27124?
CVE-2026-27124 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-2026-27124?
Yes. A fix has been recorded for CVE-2026-27124. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-27124 affect?
CVE-2026-27124 affects FastMCP MCP server OAuthProxy (GitHub OAuth integration) < 3.2.0. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-27124?
Upgrade to 3.2.0+; review OAuth consent logic.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
OAuth consent bypass enables an attacker to act as a user by exploiting GitHub OAuth consent handling.
Patch when possible
- affected< 3.2.0
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.