Description
Jansson, possibly 2.4 and earlier, does not restrict the ability to trigger hash collisions predictably, which allows context-dependent attackers to cause a denial of service (CPU consumption) via a crafted JSON document.
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 | jansson | 2.6-1 | — |
| Debian 13 | jansson | 2.6-1 | — |
| Debian 12 | jansson | 2.6-1 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 14.04 LTS | jansson | 2.5-2ubuntu0.1 | — |
Advisories 1
- WID-SEC-2025-2843 IBM DataPower Gateway (Jansson): Schwachstelle ermöglicht Denial of Service BSI CERT-Bund (WID) · Dec 14, 2025