CVE-2026-93850
Awaiting Analysis Awaiting Analysis - Queue

Memory Exhaustion in Mattermost via Malicious PDF

Publication date: 2026-10-26

Last updated on: 2026-10-26

Assigner: Mattermost, Inc.

Description
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

CVSS Scores

EPSS Scores

Probability:
Percentile:

Meta Information

Published
2026-10-26
Last Modified
2026-10-26
Generated
2026-10-26
AI Q&A
2026-10-26
EPSS Evaluated
N/A
NVD
CVE-2026-93850
EUVD
EUVD-2026-109938

Affected Vendors & Products

Showing 4 associated CPEs
Vendor Product Version / Range
Mattermost Mattermost 11.9.0
Mattermost Mattermost 11.8.0
Mattermost Mattermost 11.7.0
Mattermost Mattermost 11.10.0

Helpful Resources

Exploitability

CWE
CWE Icon
KEV
KEV Icon
CWE ID Description
CWE-409 The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

Attack-Flow Graph

AI Quick Actions

Instant insights powered by AI
Executive Summary

This vulnerability affects Mattermost versions 11.9.x through 11.9.1, 11.8.x through 11.8.5, 11.7.x through 11.7.10, and 11.10.x through 11.10.1. It occurs when the system fails to properly limit the volume of text extracted from an uploaded PDF file. An authenticated user can exploit this by uploading a specially crafted PDF with a compressed content stream that expands into an extremely large amount of text, causing the server to exhaust its memory and crash.

Detection Guidance

Detecting this vulnerability requires checking the Mattermost server version. Use commands like 'curl -s http://your-mattermost-server/api/v4/config/client | grep Version' or check the server logs for PDF upload attempts. If the version is 11.9.x <= 11.9.1, 11.8.x <= 11.8.5, or 11.7.x <= 11.7.10, the system is vulnerable.

Impact Analysis

This vulnerability can lead to a denial of service (DoS) attack. If exploited, it may cause the Mattermost server to become unresponsive or crash, disrupting service for all users. It requires an authenticated user to upload the malicious PDF, but once triggered, it can affect the entire system's availability.

Mitigation Strategies

Upgrade Mattermost to a patched version (11.10.2 or later). If immediate upgrade is not possible, restrict PDF uploads or limit file sizes to reduce memory exhaustion risks. Monitor server memory usage for unusual spikes during PDF processing.

Chat Assistant

Ask questions about this CVE
Hi! I’m here to help you understand CVE-2026-93850. Ask me anything about the vulnerability, its impact, or mitigation strategies.
0/70

EPSS Chart