CVE-2026-4635 Vulnerability Analysis & Exploit Details

CVE-2026-4635
Vulnerability Scoring

6.5
/10
High Risk

If left unpatched, CVE-2026-4635 could lead to major system disruptions or data loss.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: Low
    Some privileges are necessary to exploit the vulnerability.
  • Scope: Unchanged
    Exploit remains within the originally vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2026-4635 Details

Status: Analyzed

Published on: 22 May 2026, 11:16 UTC

CVSS Release: version 3

CVSS3 Source

responsibledisclosure@mattermost.com

CVSS3 Type

Secondary

CVSS3 Vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVE-2026-4635 Vulnerability Summary

CVE-2026-4635: Mattermost versions 11.6.x <= 11.6.0, 11.5.x <= 11.5.3, 11.4.x <= 11.4.4, 10.11.x <= 10.11.14 fail to archive the channel before removing persistent notifications which allows authenticated user to crash the server via timing the creation of persistent notification message between the server deleting existing persistent notifications and archiving the channel.. Mattermost Advisory ID: MMSA-2026-00637

Assessing the Risk of CVE-2026-4635

Access Complexity Graph

The exploitability of CVE-2026-4635 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2026-4635

CVE-2026-4635 presents an accessible attack vector with minimal effort required. Restricting access controls and implementing security updates are critical to reducing exploitation risks.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2026-4635, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2026-4635, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2026-4635 has no significant impact on data confidentiality.
  • Integrity: None
    CVE-2026-4635 poses no threat to data integrity.
  • Availability: High
    CVE-2026-4635 can disrupt system operations, potentially causing complete denial of service (DoS).

CVE-2026-4635 References

External References

CWE Common Weakness Enumeration

CWE-362

CAPEC Common Attack Pattern Enumeration and Classification

  • Leveraging Race Conditions CAPEC-26 The adversary targets a race condition occurring when multiple processes access and manipulate the same resource concurrently, and the outcome of the execution depends on the particular order in which the access takes place. The adversary can leverage a race condition by "running the race", modifying the resource and modifying the normal execution flow. For instance, a race condition can occur while accessing a file: the adversary can trick the system by replacing the original file with their version and cause the system to read the malicious file.
  • Leveraging Time-of-Check and Time-of-Use (TOCTOU) Race Conditions CAPEC-29 This attack targets a race condition occurring between the time of check (state) for a resource and the time of use of a resource. A typical example is file access. The adversary can leverage a file access race condition by "running the race", meaning that they would modify the resource between the first time the target program accesses the file and the time the target program uses the file. During that period of time, the adversary could replace or modify the file, causing the application to behave unexpectedly.

Vulnerable Configurations

  • cpe:2.3:a:mattermost:mattermost_server:10.11.0:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.0:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.0:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.1:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.1:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.2:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.2:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.2:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.2:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.3:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.3:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.4:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.4:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.4:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.5:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.5:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.6:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.6:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.7:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.7:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.8:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.8:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.9:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.9:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.9:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.9:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.9:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.9:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.10:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.10:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.10:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.10:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.11:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.11:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.11:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.11:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.12:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.12:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.13:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.13:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.13:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.13:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.14:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.14:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:10.11.14:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:10.11.14:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.0:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.0:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.0:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.1:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.1:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.1:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.1:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.1:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.1:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.2:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.2:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.3:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.3:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.4.4:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.4.4:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.0:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.0:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.0:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.1:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.1:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.1:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.1:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.2:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.2:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.2:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.5.3:*:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.5.3:*:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.6.0:-:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.6.0:-:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc1:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc1:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc2:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc2:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc3:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc3:*:*:*:*:*:*
  • cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc4:*:*:*:*:*:*
    cpe:2.3:a:mattermost:mattermost_server:11.6.0:rc4:*:*:*:*:*:*

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