CVE-2026-66754
Assertion bug in Rouille allows crafted percent-encoded URLs to crash servers (DoS).
Is CVE-2026-66754 being exploited?
Not confirmed. CVE-2026-66754 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 0.40% probability of exploitation in the next 30 days.
How severe is CVE-2026-66754?
CVE-2026-66754 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-2026-66754?
Not known from our data. No patch reference has been recorded for CVE-2026-66754, 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-2026-66754 affect?
CVE-2026-66754 affects Rouille 0.1.6 through 3.6.2, Rust web applications using Rouille. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
What should I do about CVE-2026-66754?
Upgrade to vendor-fixed release when available; if not, normalize/validate percent-encoded paths and block suspicious requests.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
Remote unauthenticated attacker can crash Rouille-based servers or terminate the process via crafted percent-encoded URLs, causing denial of service.
Immediate action required
- affected>= 0.1.6 and <= 3.6.2
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.