CVE-2026-66729
Unauthenticated remote crash in facil.io multipart parser via crafted Content-Disposition.
Is CVE-2026-66729 being exploited?
Not confirmed. CVE-2026-66729 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 0.60% probability of exploitation in the next 30 days.
How severe is CVE-2026-66729?
CVE-2026-66729 is rated High with a CVSS score of 8.7. 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-2026-66729?
Not known from our data. No patch reference has been recorded for CVE-2026-66729, 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-2026-66729 affect?
CVE-2026-66729 affects facil.io 0.6.0 - 0.7.6, Applications using facil.io multipart MIME parser. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66729?
Upgrade to a vendor-patched release when available; block/validate multipart uploads and restrict public POST endpoints.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Unauthenticated attacker can send a crafted POST to trigger a uint32 wraparound and out-of-bounds read, crashing the worker (remote DoS).
Immediate action required
- affected>= 0.6.0 and <= 0.7.6
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.