CVE-2026-45018
Unauthenticated RCE via Chainlit /mcp when mcp.stdio enabled
Is CVE-2026-45018 being exploited?
Not confirmed. CVE-2026-45018 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 0.65% probability of exploitation in the next 30 days.
How severe is CVE-2026-45018?
CVE-2026-45018 is rated Critical. 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-2026-45018?
Yes. A fix has been recorded for CVE-2026-45018. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2026-45018 affect?
CVE-2026-45018 affects Chainlit 2.4.0rc0 - 2.11.x, Deployments with features.mcp.enabled=true and stdio transport, Servers running Chainlit process. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-45018?
Upgrade to Chainlit 2.12.0 or disable features.mcp.enabled/stdio and restrict access until patched
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated remote command execution as the Chainlit process user via POST /mcp by supplying a crafted fullCommand (shell injection, CWE-78).
Immediate action required
- affected>= 2.4.0rc0 and < 2.12.0
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.