Description
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| ultrajson | ultrajson | < 5.13.0 | — |
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 14 | ujson | 5.13.0-1 | — |
| Debian 13 | ujson | No fix yet | — |
| Debian 12 | ujson | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | ujson +1 | No fix yet | — |
| Ubuntu 26.04 LTS | ujson +1 | No fix yet | — |
| Ubuntu 25.10 | ujson +1 | No fix yet | — |
| Ubuntu 24.04 LTS | pandas | No fix yet | — |
| Ubuntu 22.04 LTS | pandas +1 | No fix yet | — |
Show 9 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | pandas | No fix yet | — |
| Ubuntu 18.04 LTS | pandas +1 | No fix yet | — |
| Ubuntu 16.04 LTS | pandas +1 | No fix yet | — |
| Ubuntu 14.04 LTS | pandas | No fix yet | — |
| Ubuntu Pro 24.04 LTS | ujson | No fix yet | — |
| Ubuntu Pro 22.04 LTS | ujson | No fix yet | — |
| Ubuntu Pro 20.04 LTS | ujson | No fix yet | — |
| Ubuntu Pro 18.04 LTS | ujson | No fix yet | — |
| Ubuntu Pro 16.04 LTS | ujson | No fix yet | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | ujson | < 5.13.0 | 5.13.0 | GHSA-3j69-69wj-xqx2 |