cPanel CVE-2026-110688
CVE-2026-110688 is one of a coordinated set of fixes in Cpanel::JSON::XS for Perl: versions before 4.80 — allow quadratic cpu use by revalidating the remaining buffer per value in incr_parse. The corrected build is Cpanel::JSON::XS 4.80, delivered to cPanel & WHM servers through the standard update channel.
What this means under a SharedLicense license
Parsing untrusted JSON with the affected Cpanel::JSON::XS builds is the exposure: CWE-407 in the advisory's own data, CVSS 7.5 — practical risk ranges from resource exhaustion to memory corruption.
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.
Reference: https://nvd.nist.gov/vuln/detail/CVE-2026-110688
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