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CVE-2026-19076

Mattermost fails to reject OAuth application sessions in account type switch, allowing account takeover via bearer token

CVSS score

4.4

EPSS probability

%0.2

Risk score

0.0

Published

11 h ago

OverviewPublic Exploits (0)NewsroomVulnerability Timeline
Patch status has not yet been verified

Resmî kaynaklarda yeterli kanıt bulunamadı. Bu sonuç “yama yok” anlamına gelmez.

Impact on My Inventory

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Vulnerability description

CVE AI research

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DayBreach AI Explanation

Verified against sources

Mattermost OAuth Session Irregularity Account Takeover Vulnerability

Sources read

1

Source agreement

Tam uyum

Evidence confidence

%55

Short explanation

Mattermost fails to reject OAuth application sessions in the account type switch endpoint, allowing permanent account takeover of an SSO-backed account via a valid OAuth bearer token (S0).

Why does it matter?

An attacker can permanently take over SSO-backed accounts by detaching them from their identity provider and changing the password (S0).

What should be done?

  • Follow the official vendor advisory (S0)
  • Upgrade to unaffected versions (S0)
Chain of evidence and sources2 verified claims

Mattermost, hesap türü değiştirme uç noktasında OAuth uygulama oturumlarını reddetmemektedir.

S0 · daybreach-canonical

Saldırganlar, POST /api/v4/users/login/switch adresine gönderilen isteklerle hesapları ele geçirebilir.

S0 · daybreach-canonical
Show the technical text from the sources

Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to reject OAuth application sessions in the account type switch endpoint, which allows an attacker with a valid OAuth bearer token for a target user to permanently take over that user's SSO-backed account by setting an attacker-controlled password and detaching the account from its identity provider via a crafted request to POST /api/v4/users/login/switch.. Mattermost Advisory ID: MMSA-2026-00758

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

CWE: CWE-863

Explanation produced with the local gemini-flash-lite-latest model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-19076 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1mattermostMattermost View
Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
4.4CVSS V31MEDIUMCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:NNVD
4.4CVSS V3_1MEDIUMCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:NCVE CNA

Patch and Remediation Guide

Solution & Remediation Advisory

Patch status unknown

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Until a patch is confirmed, follow the vendor advisory; do not read an unknown status as “no patch”.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-19076 is associated with the following CWEs:

CWE-863: Common Weakness Enumeration Entry CWE-863

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-2026-19076 weaknesses.

CAPEC-66: SQL InjectionCAPEC-126: Path TraversalCAPEC-28: OS Command Injection

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsHigh
UserGerekmiyor

Official Sources and Advisories

MMSA-2026-00758vendor-advisory

CVSS Vector Radar Chart

4.4 / 10
Attack VectorNetworkComplexityHighPrivilegesHighUser Interact.NoneConfidentialityHighIntegrityNoneAvailabilityNone

Vulnerability Scoring Details

CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:N
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredHigh privileges
User InteractionNone required
Confidentiality (Gizlilik)High
Integrity (Bütünlük)None
Availability (Erişilebilirlik)None

Yama durumu bilinmiyor

İncelenen resmî kaynaklarda yama durumu doğrulanamadı. Bu sonuç “yama yok” anlamına gelmez.

Follow the vendor

M
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Weakness Type (CWE & CAPEC)

CWE-863

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