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AvantraApplication

CVE-2026-8670

CRITICAL · 9.6 CVSS v3.1 Published 2026-05-22
Fix available
A fix is available. Upgrade to 25.3.1 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges

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
Insufficient session expiration vulnerability in syslink software AG Avantra on Linux, Windows allows Reusing Session IDs (aka Session Replay). This issue affects Avantra: before 25.3.1.

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

This is a session management vulnerability in Avantra where session IDs remain valid beyond their intended expiration time, allowing attackers to reuse (replay) stale session IDs to impersonate legitimate users. The lack of proper session invalidation enables session replay attacks where captured session tokens can be reused even after logout or timeout periods.

MitigationUpgrade Avantra to version 25.3.1 or later. Additionally, implement proper session expiration, ensure sessions are invalidated upon logout, and consider implementing session ID rotation on authentication to mitigate replay risks.

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

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
AvantraApplication
Affected:< 25.3.1

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
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
High
Availability
High

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

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 Avantra installation version
    Locate the Avantra installation directory and check the version manifest, about page, or version file. Common locations include the installation root or a version-info file within the application directory.
    Affected if The installed version is any version prior to 25.3.1 (e.g., 25.3.0, 25.2.x, 25.1.x, etc.)
  2. Locate session configuration files
    Search for session management configuration files within the Avantra installation directory. Look for files named session.properties, session-config.xml, or similar that control session behavior.
    Affected if Session configuration files exist and show that session expiration or invalidation settings are not explicitly configured, or show that server-side session invalidation is disabled.
  3. Examine session lifecycle handling
    Review the session management implementation or configuration to determine whether sessions are invalidated server-side upon logout or timeout, or if session IDs merely become unavailable client-side.
    Affected if The system relies only on client-side session removal (e.g., clearing cookies) without server-side session invalidation, or lacks explicit session invalidation logic.
  4. Check for IP or User-Agent binding
    Inspect session management configuration or code to determine whether sessions are bound to the client's IP address or User-Agent string as a mitigation.
    Affected if Session binding to IP or User-Agent is not implemented, meaning any bearer of a valid session ID can use it regardless of origin.

You are affected if your Avantra version is below 25.3.1 AND your session management relies on client-side session handling without enforced server-side session invalidation upon logout or timeout.

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.

dbcve · scoped
Upgrade available Upgrade to 25.3.1 or later
Fixed in 25.3.1
Interim mitigation

Upgrade Avantra to version 25.3.1 or later. Additionally, implement proper session expiration, ensure sessions are invalidated upon logout, and consider implementing session ID rotation on authentication to mitigate replay risks.

Recommended fix High confidence

25.3.1

  1. 1. Back up your current Avantra installation and database
  2. 2. Download Avantra version 25.3.1 from support.avantra.com
  3. 3. Stop all Avantra services
  4. 4. Install Avantra 25.3.1 following the standard upgrade procedure for your platform (Linux or Windows)
  5. 5. Verify services start successfully after upgrade
  6. 6. Test that session expiration is functioning correctly by logging in and confirming sessions expire appropriately
Caveat Review Avantra 25.3.1 release notes for any breaking changes or migration requirements specific to your environment

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Avantra Scoped from the published advisory
  • Consultation6.0 h
  • Implementation12.0 h
  • Testing10.0 h
  • Review / QA6.0 h
34.0 hours of engineering $5,940
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $9,504.

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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-2026-8670 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
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data