# CVE-2026-11443: Allegra downloadAttachment Cross-Site Scripting Authentication Bypass Vulnerability

> Remote attackers can execute arbitrary script in the context of the current user via the downloadAttachment method, potentially leading to account takeover.

- **Severity:** Medium 4.6 (`CVSS:3.0/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 12 Jun 2026
- **Updated:** 15 Jun 2026
- **Also known as:** GHSA-m8wq-7mhg-mgm7

## What is CVE-2026-11443?

CVE-2026-11443 is a medium-severity cross-site scripting vulnerability in Allegra, published on 12 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Allegra downloadAttachment Cross-Site Scripting Authentication Bypass Vulnerability. This vulnerability allows remote attackers to execute arbitrary script on affected installations of Allegra. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the downloadAttachment method. The issue results from the lack of proper validation of user-supplied data, which can lead to the injection of arbitrary script. An attacker can leverage this vulnerability to execute script in the context of the current user. Was ZDI-CAN-28236.

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

## Which versions are affected by CVE-2026-11443?


## How do I fix CVE-2026-11443?

No fix has been published for CVE-2026-11443 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-11443 being exploited?

There is no known exploitation of CVE-2026-11443 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-11443 and fix it if it is affected.

What it is: CVE-2026-11443 is a medium-severity cross-site scripting vulnerability in Allegra, published on 12 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-11443 in the wild and no public exploit code.

Affected product: Allegra. 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-2026-11443/ (Markdown: https://insights.sbomify.com/CVE-2026-11443/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-11443
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-11443
- OSV: https://osv.dev/vulnerability/CVE-2026-11443

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-11443/
Summaries are generated and may contain mistakes; the official description above is the record.