Description
Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum.
With allow_bignum, a JSON number with a fraction or exponent decodes to a Math::BigFloat, which stores the exponent separately and so decodes cheaply. Encoding it untyped or as JSON_TYPE_FLOAT writes the plain decimal form with one digit per unit of exponent. Nothing bounds the exponent, so the 12-byte text [1e30000000] encodes to 30 MB.
Untrusted JSON decoded with allow_bignum and encoded again can exhaust memory and CPU.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| — | Cpanel-JSON-XS | < 4.80 | 4.80 |
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 | libcpanel-json-xs-perl | 4.80-1 | — |
| Debian 13 | libcpanel-json-xs-perl | No fix yet | — |
| Debian 12 | libcpanel-json-xs-perl | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | libcpanel-json-xs-perl | No fix yet | — |
| Ubuntu 26.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
| Ubuntu 24.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
| Ubuntu 22.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
| Ubuntu 20.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
| Ubuntu 16.04 LTS | libcpanel-json-xs-perl | No fix yet | — |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | perl-Cpanel-JSON-XS | 4.800.0-150700.3.9.1 | SUSE-SU-2026:4926-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | perl-Cpanel-JSON-XS | 4.800.0-1.1 | openSUSE-SU-2026:12217-1 |
| openSUSE Leap 16.0 | perl-Cpanel-JSON-XS | 4.800.0-bp160.1.1 | openSUSE-SU-2026:22187-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | perl-Cpanel-JSON-XS | 4.25-2.amzn2023.0.10 | ALAS2023-2026-3352 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | perl-Cpanel-JSON-XS | No fix yet | — |
Advisories 4
- ALAS2023-2026-3352 Important: perl-Cpanel-JSON-XS security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Nov 2, 2026
- openSUSE-SU-2026:22187-1 Security update for perl-Cpanel-JSON-XS SUSE / openSUSE Security Updates · Nov 1, 2026
- SUSE-SU-2026:4926-1 Security update for perl-Cpanel-JSON-XS SUSE / openSUSE Security Updates · Oct 29, 2026
- openSUSE-SU-2026:12217-1 perl-Cpanel-JSON-XS-4.800.0-1.1 on GA media SUSE / openSUSE Security Updates · Oct 22, 2026