CVE-2026-110676 Cpanel::JSON::XS versions before 4.80 for Perl allow memory exhaustion by encoding exponent notation as full decimal digits under allow_bignum.
Attackers can cause memory exhaustion and denial of service by exploiting unbounded exponent encoding in Cpanel::JSON::XS when allow_bignum is enabled.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-110676?
CVE-2026-110676 is a high-severity denial of service vulnerability, published on 19 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Weakness: CWE-405
Which versions are affected by CVE-2026-110676?
How do I fix CVE-2026-110676?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-110676 being exploited?
There is no known exploitation of CVE-2026-110676 in the wild and no public exploit code.
Sources
Also known as AZL-109845, DEBIAN-CVE-2026-110676, GHSA-qgf5-7gf3-jg2g, UBUNTU-CVE-2026-110676.