CVE-2026-20796 Vulnerability Analysis & Exploit Details

CVE-2026-20796
Vulnerability Scoring

3.1
/10
Moderate Risk

Exploiting CVE-2026-20796 requires specific conditions, leading to a moderate security impact.

Attack Complexity Details

  • Attack Complexity: High
    Exploits require significant effort and 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-2026-20796 Details

Status: Received on 13 Feb 2026, 11:16 UTC

Published on: 13 Feb 2026, 11:16 UTC

CVSS Release: version 3

CVSS3 Source

responsibledisclosure@mattermost.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2026-20796 Vulnerability Summary

CVE-2026-20796: Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user to learn team names they should not have access to via a race condition in the /common_teams API endpoint.. Mattermost Advisory ID: MMSA-2025-00549

Assessing the Risk of CVE-2026-20796

Access Complexity Graph

The exploitability of CVE-2026-20796 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-2026-20796

This vulnerability, CVE-2026-20796, requires a high level of attack complexity and low privileges, making it difficult but not impossible to exploit. Organizations should ensure robust security configurations to mitigate 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-2026-20796, 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-2026-20796, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: Low
    CVE-2026-20796 could lead to minor leaks of non-critical information without major privacy breaches.
  • Integrity: None
    CVE-2026-20796 poses no threat to data integrity.
  • Availability: None
    CVE-2026-20796 does not impact system availability.

CVE-2026-20796 References

External References

CWE Common Weakness Enumeration

CWE-367

CAPEC Common Attack Pattern Enumeration and Classification

  • Leveraging Race Conditions via Symbolic Links CAPEC-27 This attack leverages the use of symbolic links (Symlinks) in order to write to sensitive files. An attacker can create a Symlink link to a target file not otherwise accessible to them. When the privileged program tries to create a temporary file with the same name as the Symlink link, it will actually write to the target file pointed to by the attackers' Symlink link. If the attacker can insert malicious content in the temporary file they will be writing to the sensitive file by using the Symlink. The race occurs because the system checks if the temporary file exists, then creates the file. The attacker would typically create the Symlink during the interval between the check and the creation of the temporary 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.

Protect Your Infrastructure against CVE-2026-20796: Combat Critical CVE Threats

Stay updated with real-time CVE vulnerabilities and take action to secure your systems. Enhance your cybersecurity posture with the latest threat intelligence and mitigation techniques. Develop the skills necessary to defend against CVEs and secure critical infrastructures. Join the top cybersecurity professionals safeguarding today's infrastructures.

Other 5 Recently Published CVEs Vulnerabilities

  • CVE-2026-2443 – A flaw was identified in libsoup, a widely used HTTP library in GNOME-based systems. When processing specially crafted HTTP Range headers, the libr...
  • CVE-2025-33042 – Improper Control of Generation of Code ('Code Injection') vulnerability in Apache Avro Java SDK when generating specific records from untrusted Avr...
  • CVE-2026-22892 – Mattermost versions 11.1.x <= 11.1.2, 10.11.x <= 10.11.9, 11.2.x <= 11.2.1 fail to validate user permissions when creating Jira issues from Matterm...
  • CVE-2026-20796 – Mattermost versions 10.11.x <= 10.11.9 fail to properly validate channel membership at the time of data retrieval which allows a deactivated user t...
  • CVE-2026-0872 – Improper Certificate Validation vulnerability in Thales SafeNet Agent for Windows Logon on Windows allows Signature Spoofing by Improper Validation...