# CVE-2026-50055: Zimbra Collaboration Suite Sieve Notify Filter Action Bypasses Mail Forwarding Restriction via Variable Expansion

> Authenticated users can bypass mail forwarding restrictions using Sieve notify actions to exfiltrate email content and headers to arbitrary addresses.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Oct 2026
- **Updated:** 8 Oct 2026
- **Also known as:** GHSA-p88h-r6ph-r7j6

## What is CVE-2026-50055?

CVE-2026-50055 is a medium-severity vulnerability in Zimbra Collaboration Suite, published on 8 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A policy-enforcement flaw in Zimbra Collaboration Suite allows an authenticated user to bypass disabled mail forwarding by using a Sieve notify action to send copies of email content and headers to an arbitrary address.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-50055?


## How do I fix CVE-2026-50055?

No fix has been published for CVE-2026-50055 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-50055 being exploited?

There is no known exploitation of CVE-2026-50055 in the wild and no public exploit code.

Public exploit code:

- CVE-2026-50055 - Draft (github_poc): https://github.com/HORKimhab/CVE-2026-50055

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50055 and fix it if it is affected.

What it is: CVE-2026-50055 is a medium-severity vulnerability in Zimbra Collaboration Suite, published on 8 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-50055 in the wild and no public exploit code.

Affected product: Zimbra Collaboration Suite. 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-2026-50055/ (Markdown: https://insights.sbomify.com/CVE-2026-50055/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50055
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50055
- OSV: https://osv.dev/vulnerability/CVE-2026-50055

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50055/
Summaries are generated and may contain mistakes; the official description above is the record.