Description
Mojo::JSON versions before 9.47 for Perl allow memory exhaustion via unbounded recursion in the pure-Perl decoder.
The pure-Perl decode path (`_decode_value` dispatching to `_decode_array` and `_decode_object`) recurses with no depth limit, so a small deeply nested JSON document can consume excessive memory.
This path is the default when Cpanel::JSON::XS is not installed or `MOJO_NO_JSON_XS=1` is set; the Cpanel::JSON::XS fast path is not affected.
Any caller that decodes an untrusted JSON body, for example `Mojo::Message::json` reached through `$c->req->json`, can exhaust process memory and cause denial of service.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| SRI | Mojo::JSON | < 9.47 | 9.47 |
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 | libmojolicious-perl | 9.47+dfsg-1 | — |
| Debian 13 | libmojolicious-perl | No fix yet | — |
| Debian 12 | libmojolicious-perl | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libmojolicious-perl | No fix yet | — |
| Ubuntu 26.04 LTS | libmojolicious-perl | No fix yet | — |
| Ubuntu 25.10 | libmojolicious-perl | No fix yet | — |
| Ubuntu 24.04 LTS | libmojolicious-perl | No fix yet | — |
| Ubuntu 22.04 LTS | libmojolicious-perl | No fix yet | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | libmojolicious-perl | No fix yet | — |
| Ubuntu 18.04 LTS | libmojolicious-perl | No fix yet | — |
| Ubuntu 16.04 LTS | libmojolicious-perl | No fix yet | — |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | perl-Test-Mojo +1 | 9.48-2.amzn2023.0.1 | ALAS2023-2026-3209 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | perl-Mojolicious | No fix yet | — |
Advisories 1
- ALAS2023-2026-3209 Moderate: perl-Mojolicious security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026