# CVE-2026-50053: Zimbra Collaboration Suite RestFilter Request Attribute Override via Unauthenticated URL Parameters


- **Severity:** High 8.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Fix available:** No
- **Published:** 23 Oct 2026
- **Updated:** 28 Oct 2026
- **Also known as:** GHSA-vffh-47xc-pr68

## What is CVE-2026-50053?

CVE-2026-50053 is a high-severity vulnerability in Zimbra Collaboration Suite, published on 23 Oct 2026. 

### Official description

A request attribute override vulnerability in Zimbra Collaboration Suite (ZCS) allows unauthenticated requests to /h/* to populate servlet attributes intended for trusted internal dispatch. RestFilter copies URL parameters specifying an authentication token, target account, target item and dispatch state into the request attributes consumed by the Classic Web Client. Combined with CVE-2026-10632 on ZCS 10.1.16, this allows an attacker to supply their own valid token and document identifiers and execute JavaScript in another user's signed-in browser session. ZCS 10.1.17 blocks that XSS chain by changing the document renderer, but retains the request attribute override.

Weakness: CWE-642 (External Control of Critical State Data)

## Which versions are affected by CVE-2026-50053?


## How do I fix CVE-2026-50053?

No fix has been published for CVE-2026-50053 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-50053 being exploited?

There is no known exploitation of CVE-2026-50053 in the wild and no public exploit code.

Public exploit code:

- Offline Python detector for CVE-2026-50053 version exposure in Zimbra Collaboration Suite. (github_poc): https://github.com/mehmet-emir-eroglu/CVE-2026-50053

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-50053 and fix it if it is affected.

What it is: CVE-2026-50053 is a high-severity vulnerability in Zimbra Collaboration Suite, published on 23 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-50053 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-2026-50053/ (Markdown: https://insights.sbomify.com/CVE-2026-50053/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-50053
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-50053
- OSV: https://osv.dev/vulnerability/CVE-2026-50053

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-50053/
Summaries are generated and may contain mistakes; the official description above is the record.