# CVE-2026-110673: Cpanel::JSON::XS versions before 4.80 for Perl allow stack exhaustion via nested tagged values under allow_tags in decode_tag.

> Attackers can cause a segmentation fault and crash applications using Cpanel::JSON::XS by sending deeply nested tagged JSON values when allow_tags is enabled.

- **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:** AZL-109842, DEBIAN-CVE-2026-110673, GHSA-fgcx-mvpm-hff9, UBUNTU-CVE-2026-110673

## What is CVE-2026-110673?

CVE-2026-110673 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 stack exhaustion via nested tagged values under allow_tags in decode_tag.

With allow_tags, "(" starts a tagged value. Its tag and value are decoded recursively, and each can start another tagged value. Unlike arrays and objects, this nesting is not counted against max_depth.

A run of "(" bytes exhausts the C stack and triggers an uncatchable segmentation fault regardless of max_depth.

Weakness: CWE-674 (Uncontrolled Recursion)

## Which versions are affected by CVE-2026-110673?


## How do I fix CVE-2026-110673?

Upgrade to a fixed version.

## Is CVE-2026-110673 being exploited?

There is no known exploitation of CVE-2026-110673 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-110673 and fix it if it is affected.

What it is: CVE-2026-110673 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-2026-110673 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-2026-110673/ (Markdown: https://insights.sbomify.com/CVE-2026-110673/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-110673
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-110673
- OSV: https://osv.dev/vulnerability/CVE-2026-110673

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-110673/
Summaries are generated and may contain mistakes; the official description above is the record.