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Authorization Bypass (IDOR)Weakness · CWE-639

CVE-2026-15389

HIGH · 8.7 CVSS v4.0 Published 2026-07-14
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
96/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click 5 weeks old

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

The Sesame Time application uses the session identifier (USID) as the sole validation mechanism without verifying ownership, allowing attackers with a valid USID to hijack user sessions and access confidential data including emails, user IDs, roles, and corporate data. Additionally, new logins generate fresh USIDs without invalidating previous ones, enabling multiple concurrent sessions and expanding the attack surface.

MitigationImplement proper session ownership validation by binding sessions to user identity and requiring verification that the USID legitimately belongs to the requesting user. Additionally, revoke previous sessions upon new login to prevent session accumulation and reduce the attack surface.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
Authentication
X
User interaction
None
Scope
X

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify Sesame Time installation
    Search for Sesame Time application files, services, or processes in the environment. Check common installation directories, web server roots, or application inventories.
    Affected if Sesame Time is found installed in the environment
  2. Determine installed version
    Locate the version file, about page, or executable metadata for Sesame Time. Common locations include: installation directory readme/version files, application binary properties, or API/frontend version endpoints.
    Affected if The installed version matches or falls within the affected version range (if known); otherwise, assume all versions are potentially affected since no safe version is specified
  3. Verify session ownership validation
    Inspect the session validation logic in the application source code or binaries. Look for authentication handlers that validate USID against user identity versus only checking USID existence. Search for code patterns where session is accepted without verifying the requesting user owns that USID.
    Affected if Code shows USID is validated by existence alone without binding to user identity or requiring ownership proof
  4. Check for concurrent session behavior
    Create two separate login sessions from different browsers/devices using the same user credentials. Query the session store or backend to determine if both USIDs remain valid simultaneously. Alternatively, review authentication code for session invalidation logic on new login.
    Affected if Multiple USIDs remain valid for the same user account after creating new sessions, indicating previous sessions are not revoked on new login
  5. Inspect session configuration
    Review application configuration files, session management settings, or database session tables. Check if there is a mechanism to limit concurrent sessions or invalidate old sessions programmatically.
    Affected if No session limit or invalidation policy is configured, allowing unlimited concurrent sessions per user

If Sesame Time is installed and the application validates sessions by USID existence alone without verifying ownership or invalidating previous sessions on new login, the environment is affected by this vulnerability.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Implement proper session ownership validation by binding sessions to user identity and requiring verification that the USID legitimately belongs to the requesting user. Additionally, revoke previous sessions upon new login to prevent session accumulation and reduce the attack surface.

Have this fixed Scoped from the published advisory
  • Consultation6.0 h
  • Implementation20.0 h
  • Testing12.0 h
  • Review / QA6.0 h
44.0 hours of engineering $7,680
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-15389 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
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  • Version or environment caveats, and links to real fixes
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