# CVE-2026-5090: Template::Plugin::HTML versions before 3.103 for Perl allows HTML and JavaScript to be injected

> An attacker can inject limited HTML and JavaScript via unescaped single quotes in the html_filter function of the Perl Template::Plugin::HTML library.

- **Severity:** Medium 6.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 19 May 2026
- **Updated:** 19 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-5090, GHSA-xhg9-j279-j625, MGASA-2026-0166, UBUNTU-CVE-2026-5090, USN-8377-1

## What is CVE-2026-5090?

CVE-2026-5090 is a medium-severity cross-site scripting vulnerability, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official description

Template::Plugin::HTML versions before 3.103 for Perl allows HTML and JavaScript to be injected.

The html_filter function did not escape single quotes. HTML attributes inside of single quotes could be have code injected.  For example, the variable "var" in

    <a id='ref' title='[% var | html %]'>

would not be properly escaped. An attacker could insert some limited HTML and JavaScript, for example,

    var = " ' onclick='while (true) { alert(1) }'"

Note that arbitrary HTML and JavaScript would be difficult to inject, because angle brackets, ampersands and double-quotes would still be escaped.

Weakness: CWE-79 (Improper Neutralization of Input During Web Page Generation)

## Which versions are affected by CVE-2026-5090?


## How do I fix CVE-2026-5090?

Upgrade to a fixed version.

## Is CVE-2026-5090 being exploited?

There is no known exploitation of CVE-2026-5090 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-5090 and fix it if it is affected.

What it is: CVE-2026-5090 is a medium-severity cross-site scripting vulnerability, published on 19 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-5090 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-2026-5090/ (Markdown: https://insights.sbomify.com/CVE-2026-5090/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-5090
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-5090
- OSV: https://osv.dev/vulnerability/CVE-2026-5090

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-5090/
Summaries are generated and may contain mistakes; the official description above is the record.