---
id: "CVE-2026-93850"
kind: "vulnerability"
aliases: ["CVE-2026-93850"]
title: "Mattermost: crafted PDF upload can exhaust server memory, causing denial of service"
severity: "medium"
cvss: 6.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["mattermost", "package", "self-hosted"]
not_affected_if: ["auth-required", "managed-hosting"]
published_at: "2026-10-26T15:16:46+00:00"
first_seen_at: "2026-10-26T16:02:26+00:00"
updated_at: "2026-10-26T16:03:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-93850", "first_seen_at": "2026-10-26T16:02:26+00:00"}]
---

# Mattermost: crafted PDF upload can exhaust server memory, causing denial of service

Mattermost fails to limit how much text it extracts from an uploaded PDF, so a crafted PDF with a compressed stream that expands hugely can consume all server memory. An authenticated user can crash or stall the server by uploading it.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the Mattermost server version with `mattermost version` or the System Console; versions 11.7.x through 11.7.10, 11.8.x through 11.8.5, 11.9.x through 11.9.1 and 11.10.x through 11.10.1 are affected.

## Fix

- Upgrade Mattermost to a fixed release for your branch; the specific fixed versions are unknown from the sources.
- Check the Mattermost advisory MMSA-2026-00769 for the patched build numbers.

## Timeline

- 2026-10-26T16:02:26+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-93850

## From the sources

Mattermost versions 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, 11.7.x <= 11.7.10, 11.10.x <= 11.10.1 fail to bind the volume of text extracted from an uploaded PDF which allows an authenticated user to exhaust server memory and cause a denial of service via a crafted PDF whose compressed content stream expands into a very large amount of text.. Mattermost Advisory ID: MMSA-2026-00769

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_