# CVE-2026-9516: Denial of service in Cpanel::JSON::XS

> Attackers can crash Perl applications using Cpanel::JSON::XS by sending UTF-8 BOM prefixed JSON that triggers a filter callback exception.

- **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:** 3 Jun 2026
- **Updated:** 3 Jun 2026
- **Also known as:** AZL-89399, DEBIAN-CVE-2026-9516, GHSA-32gp-2g42-v9vc, UBUNTU-CVE-2026-9516

## What is CVE-2026-9516?

CVE-2026-9516 is a high-severity denial of service vulnerability in RURBAN Cpanel::JSON::XS, published on 3 Jun 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 4.41 for Perl allow denial of service via UTF-8 BOM prefixed input when a decode filter callback throws.

To skip a leading 3-byte UTF-8 BOM, decode_json() advances the input scalar's string pointer past the mark with SvPV_set() and restores it only on the normal return path. When decoding aborts through a Perl exception, for example a filter_json_object callback that croaks, the restore is skipped and the scalar is left with its string pointer offset into its own buffer and a shortened length.

When that scalar is later freed, the allocator receives an invalid pointer and the interpreter aborts. A single BOM prefixed document decoded with a throwing filter callback crashes any caller.

Weakness: CWE-763 (Release of Invalid Pointer or Reference), CWE-755 (Improper Handling of Exceptional Conditions)

## Which versions are affected by CVE-2026-9516?

It affects 1 product.


Products: Rurban Cpanel\.

## How do I fix CVE-2026-9516?

Upgrade to a fixed version.

## Is CVE-2026-9516 being exploited?

There is no known exploitation of CVE-2026-9516 in the wild and no public exploit code.

## Other vulnerabilities in RURBAN Cpanel::JSON::XS

- [CVE-2022-48623](https://insights.sbomify.com/CVE-2022-48623/): Information disclosure in n/a (critical 9.1)
- [CVE-2026-9334](https://insights.sbomify.com/CVE-2026-9334/): Memory corruption in Cpanel::JSON::XS (high 7.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-9516 and fix it if it is affected.

What it is: CVE-2026-9516 is a high-severity denial of service vulnerability in RURBAN Cpanel::JSON::XS, published on 3 Jun 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-2026-9516 in the wild and no public exploit code.

Affected product: RURBAN Cpanel::JSON::XS. No package-level version data is available, so check the vendor advisory linked from the reference page.

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-2026-9516/ (Markdown: https://insights.sbomify.com/CVE-2026-9516/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-9516
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-9516
- OSV: https://osv.dev/vulnerability/CVE-2026-9516

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-9516/
Summaries are generated and may contain mistakes; the official description above is the record.