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CWE-191Weakness · CWE-191

CVE-2026-25075

HIGH · 7.5 CVSS v3.1 Published 2026-03-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
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
strongSwan versions 4.5.0 prior to 6.0.5 contain an integer underflow vulnerability in the EAP-TTLS AVP parser that allows unauthenticated remote attackers to cause a denial of service by sending crafted AVP data with invalid length fields during IKEv2 authentication. Attackers can exploit the failure to validate AVP length fields before subtraction to trigger excessive memory allocation or NULL pointer dereference, crashing the charon IKE daemon.

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

strongSwan versions 4.5.0 through 6.0.4 contain an integer underflow in the EAP-TTLS AVP parser where the code performs subtraction on AVP length fields without proper validation, allowing attackers to trigger excessive memory allocation or NULL pointer dereference by sending crafted AVP data with invalid length fields during IKEv2 authentication, causing the charon IKE daemon to crash.

MitigationUpgrade strongSwan to version 6.0.5 or later to patch the integer underflow vulnerability in the EAP-TTLS AVP parser; alternatively, disable EAP-TTLS authentication methods if upgrading is not immediately feasible.

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
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Verify strongSwan installation
    Run 'strongswan -v' or 'ipsec --version' to display the installed version, or check package manager (dpkg -l | grep strongswan, rpm -qa | grep strongswan)
    Affected if strongSwan is installed and the version is earlier than 6.0.5
  2. Confirm charon daemon is running
    Run 'ps aux | grep charon' or check systemctl status strongswan
    Affected if The charon daemon process is active, as this is the vulnerable component
  3. Identify if EAP-TTLS is configured
    Review /etc/ipsec.conf and /etc/ipsec.d/ for 'eap-ttls' or 'EAP-TTLS' in the leftauth/rightauth parameters, or check VPN connection profiles
    Affected if EAP-TTLS authentication method is defined in the ipsec configuration
  4. Check IKEv2 responder configuration
    Examine /etc/ipsec.conf for 'keyexchange=ikev2' and listen addresses to confirm the system acts as a VPN gateway accepting IKEv2 connections
    Affected if The system is configured as an IKEv2 VPN responder that processes incoming authentication requests

A system is affected if it runs strongSwan versions before 6.0.5 with the charon daemon and has EAP-TTLS authentication enabled for IKEv2 connections.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade strongSwan to version 6.0.5 or later to patch the integer underflow vulnerability in the EAP-TTLS AVP parser; alternatively, disable EAP-TTLS authentication methods if upgrading is not immediately feasible.

Recommended fix Moderate confidence

strongSwan 6.0.5 or later stable release

  1. 1. Identify the current installed version of strongSwan using 'ipsec version' or checking package manager
  2. 2. If version is between 4.5.0 and 6.0.4 inclusive, plan upgrade to version 6.0.5 or later
  3. 3. Obtain strongSwan from official source: https://www.strongswan.org/
  4. 4. Review strongSwan 6.0.5 release notes to confirm the EAP-TTLS AVP parser vulnerability is addressed
  5. 5. Test the upgrade in a non-production environment first
  6. 6. Apply the upgrade via package manager or compile from source following strongSwan installation documentation
  7. 7. After upgrade, verify charon daemon starts successfully with 'ipsec start' and 'ipsec status'
Caveat Review release notes for any configuration or feature changes between your current version and 6.0.5; major version jumps may require configuration adjustments

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

Have this fixed Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing4.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,280
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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-2026-25075 in production — separate from our analysis above.

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What this is

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