dbcve.org
Ubuntu LinuxOperating system · Canonical

CVE-2015-8023

MEDIUM · 5.0 CVSS v2.0 Published 2015-11-18
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
Remotely reachable No privileges Zero-click

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
The server implementation of the EAP-MSCHAPv2 protocol in the eap-mschapv2 plugin in strongSwan 4.2.12 through 5.x before 5.3.4 does not properly validate local state, which allows remote attackers to bypass authentication via an empty Success message in response to an initial Challenge message.

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 eap-mschapv2 plugin in strongSwan 4.2.12 through 5.x before 5.3.4 fails to properly validate local state in its server-side EAP-MSCHAPv2 implementation. A remote attacker can send an empty Success message in response to the server's initial Challenge message, bypassing the authentication mechanism.

MitigationUpgrade strongSwan to version 5.3.4 or later to obtain the patched code that properly validates state before accepting authentication responses.

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
Ubuntu LinuxOperating system
Affected:= 14.04= 15.04= 15.10
StrongswanApplication
Affected:= 4.2.12= 4.2.13= 4.2.14= 4.2.15= 4.2.16= 4.3.0= 4.3.1= 4.3.2= 4.3.3= 4.3.4= 4.3.5= 4.3.6

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
Authentication
None
Confidentiality
None
Integrity
Partial
Availability
None

AV:N/AC:L/Au:N/C:N/I:P/A:N

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. Check if strongSwan is installed
    Run 'dpkg -l | grep strongswan' on Debian/Ubuntu, or 'strongswan --version' to get version information
    Affected if strongSwan is installed and the version is between 4.2.12 and 5.3.3 inclusive, or if the exact version matches one of the listed affected versions (4.2.12 through 4.3.6)
  2. Identify the exact installed version
    Run 'ipsec --version' or check the package manager output for the installed strongswan package version
    Affected if The installed version is 5.x before 5.3.4, or any version in the 4.2.12 through 4.3.6 range
  3. Verify the eap-mschapv2 plugin is loaded
    Check the ipsec.conf configuration file at /etc/ipsec.conf for 'eap-mschapv2' in the rightauth or authby settings, or run 'ipsec statusall' to see loaded plugins
    Affected if The eap-mschapv2 plugin is enabled and the system is configured as an EAP-MSCHAPv2 authenticator (server)
  4. Confirm server-side EAP-MSCHAPv2 configuration
    Inspect /etc/ipsec.conf and related ipsec.d/ configurations for 'rightauth' or 'authby' settings using 'eap-mschapv2' for a remote access VPN server
    Affected if The system is configured as a VPN server authenticating clients using EAP-MSCHAPv2 (server-side authentication)
  5. Check if strongSwan is acting as an authentication server
    Review the ipsec.conf 'left' and 'right' definitions; the 'left' side typically represents the server; verify that eap-mschapv2 is used for authenticating remote clients
    Affected if strongSwan is configured as a server accepting EAP-MSCHAPv2 authentication from remote clients

You are affected if strongSwan with a version between 4.2.12 and 5.3.3 is installed AND the eap-mschapv2 plugin is enabled for server-side authentication (VPN gateway role).

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

Upgrade strongSwan to version 5.3.4 or later to obtain the patched code that properly validates state before accepting authentication responses.

Fix this in Ubuntu Linux Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2015-8023 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2015-8023 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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