CVE-2026-110688 Cpanel::JSON::XS versions from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the remaining buffer per value in incr_parse.
A remote attacker can cause denial of service by sending crafted non-ASCII JSON data, triggering excessive CPU usage in the Perl Cpanel::JSON::XS library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-110688?
CVE-2026-110688 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 from 4.51 before 4.80 for Perl allow quadratic CPU use by revalidating the remaining buffer per value in incr_parse.
At the first non-ASCII byte in a string, the decoder validates UTF-8 from there to the end of its input. incr_parse decodes each buffered value with a fresh decoder, so every value revalidates the rest of the buffer, and doubling the input quadruples the work.
A peer that sends about a megabyte of ordinary non-ASCII JSON in one read ties up the process for seconds of CPU time.
Weakness: CWE-407
Which versions are affected by CVE-2026-110688?
How do I fix CVE-2026-110688?
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-2026-110688 being exploited?
There is no known exploitation of CVE-2026-110688 in the wild and no public exploit code.
Sources
Also known as DEBIAN-CVE-2026-110688, GHSA-cv8j-jrx6-q4fj, UBUNTU-CVE-2026-110688.