Facil.Io

A security flaw has been discovered in boazsegev facil.io up to 0.7.58. This affects the function http_sendfile2 of the file lib/facil/http/http.c of the component Public Folder Handler. Performing a manipulation results in path traversal. Remote exploitation of the attack is possible. The exploit has been released to the public and may be used for attacks. The project was informed of the problem early through an issue report but has not responded yet.

Published: 2026-07-23T01:15:11.052Z
Updated: 2026-07-23T16:06:10.749Z

A flaw has been found in boazsegev facil.io up to 0.7.4. Affected is the function websocket_on_protocol_error in the library lib/facil/http/parsers/websocket_parser.h of the component WebSocket Frame Parser. This manipulation of the argument on_message causes improper input validation. The attack can be initiated remotely. The exploit has been published and may be used. The project was informed of the problem early through an issue report but has not responded yet.

Published: 2026-07-22T23:45:10.246Z
Updated: 2026-07-23T15:36:53.311Z

facil.io is a C micro-framework for web applications. Prior to commit 5128747363055201d3ecf0e29bf0a961703c9fa0, `fio_json_parse` can enter an infinite loop when it encounters a nested JSON value starting with `i` or `I`. The process spins in user space and pegs one CPU core at ~100% instead of returning a parse error. Because `iodine` vendors the same parser code, the issue also affects `iodine` when it parses attacker-controlled JSON. The smallest reproducer I found is `[i`. The quoted-value form that originally exposed the issue, `[""i`, reaches the same bug because the parser tolerates missing commas and then treats the trailing `i` as the start of another value. Commit 5128747363055201d3ecf0e29bf0a961703c9fa0 fixes the issue.

Published: 2026-04-22T01:07:28.660Z
Updated: 2026-04-22T13:09:38.075Z