CVE-2026-15389

Inadequate access control in Sesame Time session management

Published Jul 14, 2026 CVSS 4.0 · 8.7 High EPSS < 1% KEV · Not listed
Description
A vulnerability relating to insufficient access control has been identified in the session management of the Sesame Time web application and its REST v3 API. The flaw lies in the fact that the system uses the session identifier (USID) as the sole validation mechanism, without verifying whether that identifier legitimately belongs to the user making the request. As a result, an attacker who obtains a valid USID can impersonate a victim’s session and access their confidential information, including emails, user IDs, roles and corporate data. This vulnerability is exacerbated by poor session lifecycle management: new logins generate additional USIDs without revoking the previous ones, allowing multiple active sessions to coexist and thereby expanding the attack surface.

Remediation

Vendor Solution

The vulnerability has been fixed by the Sesame Time team in the latest available version. The update includes improvements to the authentication mechanism and strengthens authorisation checks on the server to ensure that each session can only access information associated with the authenticated user.

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
First Time appeared Sesame Time
Sesame Time sesame Time
Vendors & Products Sesame Time
Sesame Time sesame Time
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A vulnerability relating to insufficient access control has been identified in the session management of the Sesame Time web application and its REST v3 API. The flaw lies in the fact that the system uses the session identifier (USID) as the sole validation mechanism, without verifying whether that identifier legitimately belongs to the user making the request. As a result, an attacker who obtains a valid USID can impersonate a victim’s session and access their confidential information, including emails, user IDs, roles and corporate data. This vulnerability is exacerbated by poor session lifecycle management: new logins generate additional USIDs without revoking the previous ones, allowing multiple active sessions to coexist and thereby expanding the attack surface.
Title Inadequate access control in Sesame Time session management
Weaknesses CWE-639
References
Metrics cvssV4_0

{'score': 8.7, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
INCIBE
Published
Updated
Jul 14, 2026, 12:08 PM
Reserved
Jul 10, 2026, 11:40 AM
Status
Deferred
Published
Jul 14, 2026, 11:16 AM
Modified
Jul 15, 2026, 7:50 PM