# 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.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 Oct 2026
- **Updated:** 29 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-110688, GHSA-cv8j-jrx6-q4fj, UBUNTU-CVE-2026-110688

## 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 (Inefficient Algorithmic Complexity)

## Which versions are affected by CVE-2026-110688?


## How do I fix CVE-2026-110688?

Upgrade to a fixed version.

## Is CVE-2026-110688 being exploited?

There is no known exploitation of CVE-2026-110688 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110688 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-110688 in the wild and no public exploit code.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-110688/ (Markdown: https://insights.sbomify.com/CVE-2026-110688/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110688
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110688
- OSV: https://osv.dev/vulnerability/CVE-2026-110688

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-110688/
Summaries are generated and may contain mistakes; the official description above is the record.