Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1 WebSocket Msgpack Decoder allocation of resources

CVSS Meta Temp Score
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CTI Interest Score
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5.3$0-$5k0.92

Summaryinfo

A vulnerability was found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1 and classified as problematic. Impacted is an unknown function of the component WebSocket Msgpack Decoder. The manipulation results in allocation of resources. This vulnerability is identified as CVE-2026-93849. The attack can be executed remotely. There is not any exploit available. It is suggested to upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, was found in Mattermost up to 11.7.10/11.8.5/11.9.1/11.10.1. Affected is an unknown code of the component WebSocket Msgpack Decoder. The manipulation with an unknown input leads to a allocation of resources vulnerability. CWE is classifying the issue as CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. This is going to have an impact on availability. CVE summarizes:

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 Mattermost fail to apply allocation limits to the byte-string decode paths in its WebSocket msgpack decoder, which allows an authenticated remote attacker to cause excessive server memory allocation via a crafted binary WebSocket frame declaring a Bin32 payload length of up to 4,294,967,295 bytes.. Mattermost Advisory ID: MMSA-2026-00768

The advisory is available at mattermost.com. This vulnerability is traded as CVE-2026-93849 since 09/18/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. The technical details are unknown and an exploit is not available. This vulnerability is assigned to T1499 by the MITRE ATT&CK project.

Upgrading to version 11.7.11, 11.8.6, 11.9.2, 11.10.2 or 11.11.0 eliminates this vulnerability.

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Productinfo

Type

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.3

VulDB Base Score: 4.3
VulDB Temp Score: 4.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (Mattermost): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Allocation of resources
CWE: CWE-770 / CWE-400 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Mattermost 11.7.11/11.8.6/11.9.2/11.10.2/11.11.0

Timelineinfo

09/18/2026 CVE reserved
10/26/2026 +38 days Advisory disclosed
10/26/2026 +0 days VulDB entry created
10/26/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: mattermost.com
Status: Confirmed

CVE: CVE-2026-93849 (🔒)
GCVE (CVE): GCVE-0-2026-93849
GCVE (VulDB): GCVE-100-426486

Entryinfo

Created: 10/26/2026 16:26
Changes: 10/26/2026 16:26 (63)
Complete: 🔍
Cache ID: 216::103

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