CVE-2026-10819
Mattermost Server Denial of Service via Animated GIF Emoji Upload
Description
Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695
INFO
Published Date :
July 27, 2026, 3:16 p.m.
Last Modified :
July 27, 2026, 4:17 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-10819
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | MEDIUM | 9302f53e-dde5-4bf3-b2f2-a83f91ac0eee | ||||
| CVSS 3.1 | MEDIUM | [email protected] |
Solution
- Update Mattermost to a non-vulnerable version.
- Apply vendor security patches promptly.
- Review file upload configurations.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-10819.
| URL | Resource |
|---|---|
| https://mattermost.com/security-updates |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-10819 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-10819
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-10819 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-10819 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 27, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-10819', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-27T15:05:17.249105Z'} -
New CVE Received by [email protected]
Jul. 27, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'Mattermost', 'product': 'Mattermost', 'versions': [{'status': 'affected', 'version': '11.6.0', 'versionType': 'semver', 'lessThanOrEqual': '11.6.5'}, {'status': 'affected', 'version': '10.11.0', 'versionType': 'semver', 'lessThanOrEqual': '10.11.20'}, {'status': 'affected', 'version': '11.8.0', 'versionType': 'semver', 'lessThanOrEqual': '11.8.1'}, {'status': 'affected', 'version': '11.7.0', 'versionType': 'semver', 'lessThanOrEqual': '11.7.4'}, {'status': 'unaffected', 'version': '11.9.0'}, {'status': 'unaffected', 'version': '11.6.6'}, {'status': 'unaffected', 'version': '10.11.21'}, {'status': 'unaffected', 'version': '11.8.2'}, {'status': 'unaffected', 'version': '11.7.5'}], 'defaultStatus': 'unaffected'}] Added Description Mattermost versions 11.6.x <= 11.6.5, 10.11.x <= 10.11.20, 11.8.x <= 11.8.1, 11.7.x <= 11.7.4 fail to limit the number of frames and enforce the file size cap on animated GIF uploads, which allows an authenticated attacker to cause a denial of service via a crafted animated GIF uploaded as a custom emoji.. Mattermost Advisory ID: MMSA-2026-00695 Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H Added CWE CWE-409 Added Reference https://mattermost.com/security-updates