Description
An issue was discovered in the gon gem before gon-6.4.0 for Ruby. MultiJson does not honor the escape_mode parameter to escape fields as an XSS protection mechanism. To mitigate, json_dumper.rb in gon now does escaping for XSS by default without relying on MultiJson.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 12 | ruby-gon | 6.4.0-1 | — |
| Debian 9 | ruby-gon | 6.1.0-1+deb9u1 | DLA-2380-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | ruby-gon | No fix yet | — |
| Ubuntu 18.04 LTS | ruby-gon | 6.1.0-1+deb9u1build0.18.04.1 | USN-4560-1 |
| Ubuntu 16.04 LTS | ruby-gon | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| RubyGems | gon | < 6.4.0 | 6.4.0 | GHSA-78vq-9j56-wrfr |
Advisories 2
- USN-4560-1 ruby-gon vulnerability Ubuntu Security Notices (USN) · Apr 27, 2026
- DLA-2380-1 ruby-gon - security update Debian Security (DSA / DLA) · Mar 9, 2026