What is CVE-2026-66754?

CVE-2026-66754 is a medium-severity vulnerability in Tomaka Rouille, classified under Reachable Assertion. CVSS score: 5.9/10. Published 2026-07-28.

How severe is CVE-2026-66754?

Medium severity. CVSS v3 base score is 5.9 out of 10.

Is CVE-2026-66754 known to be exploited?

1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Vulnerability in Tomaka Rouille

CVE-2026-66754

Rouille 0.1.6 through 3.6.2 contains a reachable assertion vulnerability in the Request::remove_prefix function that allows remote unauthenticated attackers to crash the server by sending a crafted percent-encoded URL. Attackers can send a request whose decoded path matches a configured prefix while the raw percent-encoded path does not, causing the assert! to fail and triggering either a 500 error or full process termination depending on the panic configuration.

EPSS: 0.004 (33.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Tomaka Rouille — versions 0.1.6

Weakness classification (CWE)

CWE-617 — Reachable Assertion

Public proof-of-concept exploits

theopaid/CVE-2026-66754-Remote-Denial-of-Service-via-Reachable-Assertion-in-URL-Prefix-Handling-rouille-

References

disclosure@vulncheck.com (technical-description, exploit)
disclosure@vulncheck.com (third-party-advisory)

Frequently asked questions

What is CVE-2026-66754?: CVE-2026-66754 is a medium-severity vulnerability in Tomaka Rouille, classified under Reachable Assertion. CVSS score: 5.9/10. Published 2026-07-28.
How severe is CVE-2026-66754?: Medium severity. CVSS v3 base score is 5.9 out of 10.
Is CVE-2026-66754 known to be exploited?: 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.