# CVE-2026-25075: strongSwan 4.5.0 < 6.0.5 EAP-TTLS AVP Parsing Integer Underflow

CVE-2026-25075 is fixed in 26 products on 1 platform, first by DSA-6176-1, released March 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-25075
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0105
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Mar 23, 2026
- Weakness: Integer Underflow (Wrap or Wraparound)
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-25075

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | charon-cmd Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [charon-cmd 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-charon-cmd-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | charon-cmd Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [charon-cmd 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-charon-cmd-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | charon-cmd Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [charon-cmd 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-charon-cmd-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | charon-systemd Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [charon-systemd 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-charon-systemd-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | charon-systemd Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [charon-systemd 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-charon-systemd-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | charon-systemd Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [charon-systemd 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-charon-systemd-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | libcharon-extauth-plugins Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [libcharon-extauth-plugins 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcharon-extauth-plugins-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | libcharon-extauth-plugins Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [libcharon-extauth-plugins 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcharon-extauth-plugins-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | libcharon-extauth-plugins Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [libcharon-extauth-plugins 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcharon-extauth-plugins-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | libcharon-extra-plugins Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [libcharon-extra-plugins 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libcharon-extra-plugins-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | libcharon-extra-plugins Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [libcharon-extra-plugins 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libcharon-extra-plugins-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | libcharon-extra-plugins Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [libcharon-extra-plugins 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libcharon-extra-plugins-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | libstrongswan Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [libstrongswan 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libstrongswan-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | libstrongswan Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [libstrongswan 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libstrongswan-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | libstrongswan Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [libstrongswan 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libstrongswan-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | libstrongswan-extra-plugins Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [libstrongswan-extra-plugins 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libstrongswan-extra-plugins-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | libstrongswan-extra-plugins Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [libstrongswan-extra-plugins 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libstrongswan-extra-plugins-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | libstrongswan-extra-plugins Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [libstrongswan-extra-plugins 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libstrongswan-extra-plugins-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | libstrongswan-standard-plugins Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [libstrongswan-standard-plugins 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libstrongswan-standard-plugins-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | libstrongswan-standard-plugins Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [libstrongswan-standard-plugins 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libstrongswan-standard-plugins-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | libstrongswan-standard-plugins Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [libstrongswan-standard-plugins 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libstrongswan-standard-plugins-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | perl-vici Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan Debian 11.6 (bullseye) | 5.9.1-1+deb11u6 | [DLA-4512-1](https://patchblox.com/security/data/fix/linux/dla-4512-1.md) | Mar 27, 2026 |
| Linux | strongswan Debian 12.15 (bookworm) | 5.9.8-5+deb12u3 | [DSA-6176-1](https://patchblox.com/security/data/fix/linux/dsa-6176-1.md) | Mar 23, 2026 |
| Linux | strongswan Debian 13.5 (trixie) | 6.0.1-6+deb13u4 | [DSA-6176-1](https://patchblox.com/security/data/fix/linux/dsa-6176-1.md) | Mar 23, 2026 |
| Linux | strongswan Debian 14 | 6.0.5-1 | [DEBIAN-CVE-2026-25075](https://patchblox.com/security/data/fix/linux/debian-cve-2026-25075.md) | Mar 23, 2026 |
| Linux | strongswan Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan opensuse-leap 15.6 | 5.9.12-150600.3.11.1 | [SUSE-SU-2026:0979-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0979-1.md) | Mar 23, 2026 |
| Linux | strongswan opensuse-leap 16.0 | 6.0.4-160000.1.1 | [OPENSUSE-SU-2026:20547-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-20547-1.md) | Apr 16, 2026 |
| Linux | strongswan sles 15.6 | 5.9.12-150600.3.11.1 | [SUSE-SU-2026:0979-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0979-1.md) | Mar 23, 2026 |
| Linux | strongswan sles 15.7 | 5.9.14-150700.3.9.1 | [SUSE-SU-2026:0980-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0980-1.md) | Mar 23, 2026 |
| Linux | strongswan sles 16.0 | 6.0.4-160000.1.1 | [SUSE-SU-2026:21203-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-21203-1.md) | Apr 16, 2026 |
| Linux | strongswan-charon Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-charon 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-charon-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-charon Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-charon 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-charon-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-charon Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-charon 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-charon-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-charon-nm Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-charon-nm-debuginfo Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-debuginfo Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-debugsource Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-libcharon Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-libcharon 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-libcharon-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-libcharon Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-libcharon 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-libcharon-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-libcharon Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-libcharon 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-libcharon-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-libipsec Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-libipsec-debuginfo Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-nm Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-nm 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-nm-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-nm Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-nm 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-nm-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-nm Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-nm 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-nm-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-pki Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-pki 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-pki-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-pki Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-pki 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-pki-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-pki Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-pki 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-pki-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-scepclient Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-scepclient 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-scepclient-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-sqlite Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-sqlite-debuginfo Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-starter Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-starter 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-starter-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-starter Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-starter 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-starter-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-starter Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-starter 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-starter-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-swanctl Ubuntu 22.04.1 LTS (jammy) | 5.9.5-2ubuntu2.5 | [strongswan-swanctl 5.9.5-2ubuntu2.5](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-strongswan-swanctl-5.9.5-2ubuntu2.5.md) | Apr 15, 2026 |
| Linux | strongswan-swanctl Ubuntu 24.04.5 LTS (noble) | 5.9.13-2ubuntu4.24.04.2 | [strongswan-swanctl 5.9.13-2ubuntu4.24.04.2](https://patchblox.com/security/data/fix/linux/ubuntu-noble-strongswan-swanctl-5.9.13-2ubuntu4.24.04.2.md) | Apr 15, 2026 |
| Linux | strongswan-swanctl Ubuntu 25.10 (questing) | 6.0.1-6ubuntu4.2 | [strongswan-swanctl 6.0.1-6ubuntu4.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-strongswan-swanctl-6.0.1-6ubuntu4.2.md) | Apr 15, 2026 |
| Linux | strongswan-tnc-imcvs Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |
| Linux | strongswan-tnc-imcvs-debuginfo Fedora 43 | 6.0.7-2.fc43 | [FEDORA-2026-67A9805962](https://patchblox.com/security/data/fix/linux/fedora-2026-67a9805962.md) | Jun 16, 2026 |

---

Data as of 2026-11-08T00:53:09Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.