CVE-2026-41146 Uncontrolled resource consumption and loop with unreachable exit condition in facil.io and downstream iodine ruby gem
Attackers can cause a denial of service by sending malformed JSON that triggers an infinite loop in the facil.io and iodine parsers.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-41146?
CVE-2026-41146 is a high-severity denial of service vulnerability in boazsegev facil.io, published on 22 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-41146?
2 open source packages ship an affected version, including iodine.
| Package | Affected | Fixed in |
|---|---|---|
iodine RubyGems | All versions to 0.7.58 | None |
iodine RubyGems | All versions to 0.7.58 | None |
How do I fix CVE-2026-41146?
No fix has been published for CVE-2026-41146 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-41146 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41146 exists.
Sources
Also known as GHSA-2x79-gwq3-vxxm.