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.

CVSS v4.0

8.2 HIGHCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS v3.1

5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

0.40% chance of exploitation in the next 30 days, 33th percentile

Published

2026-07-28

Updated

2026-07-29

Proof-of-concept exploits (1)

• theopaid/Remote-Denial-of-Service-via-Reachable-Assertion-in-URL-Prefix-Handling-rouille-0★ · 2026-07-28

References

• CVE Record
• NVD entry

Related

• CVE-2023-27163
• CVE-2026-66729
• CVE-2026-66730
• CVE-2026-66731
• CVE-2026-66746
• CVE-2026-66748