# CVE-2026-55995: open-isns: A Double Free vulnerability in open-iscsi allows an unauthenticated MITM attacker to cause DoS

CVE-2026-55995 is fixed in 12 products on 1 platform, first by libisns0 0.97-2ubuntu0.1~esm1, released July 29, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-55995
- Priority: High
- CVSS: 7.5 (Important)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Jul 29, 2026

## Description

A Double Free vulnerability in open-iscsi allows an unauthenticated MITM attacker to cause DoS.       This issue affects open-iscsi: from ? through 56718d4e9d1a4f51c30697b5c0534144bb41c9bb.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | isns-utils RHEL 10 | 0.103-1.el10_0.1 | [RHSA-2026:60005](https://patchblox.com/security/data/fix/linux/rhsa-2026-60005.md) | Aug 13, 2026 |
| Linux | isns-utils RHEL 8 | 0:0.99-1.el8_10.1 | [RHSA-2026:53848](https://patchblox.com/security/data/fix/linux/rhsa-2026-53848.md) | Aug 13, 2026 |
| Linux | isns-utils RHEL 9 | 0:0.101-4.el9_8.1 | [RHSA-2026:53847](https://patchblox.com/security/data/fix/linux/rhsa-2026-53847.md) | Aug 13, 2026 |
| Linux | isns-utils almalinux 10 | 0.103-1.el10_2.1 | [ALSA-2026:53846](https://patchblox.com/security/data/fix/linux/alsa-2026-53846.md) | Aug 11, 2026 |
| Linux | isns-utils almalinux 8 | 0.99-1.el8_10.1 | [ALSA-2026:53848](https://patchblox.com/security/data/fix/linux/alsa-2026-53848.md) | Aug 11, 2026 |
| Linux | isns-utils almalinux 9 | 0.101-4.el9_8.1 | [ALSA-2026:53847](https://patchblox.com/security/data/fix/linux/alsa-2026-53847.md) | Aug 11, 2026 |
| Linux | isns-utils amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | isns-utils ol 10 | 0:0.103-1.el10_2.1 | [ELSA-2026-53846](https://patchblox.com/security/data/fix/linux/elsa-2026-53846.md) | Aug 11, 2026 |
| Linux | isns-utils ol 8 | 0:0.99-1.el8_10.1 | [ELSA-2026-53848](https://patchblox.com/security/data/fix/linux/elsa-2026-53848.md) | Aug 12, 2026 |
| Linux | isns-utils ol 9 | 0:0.101-4.el9_8.1 | [ELSA-2026-53847](https://patchblox.com/security/data/fix/linux/elsa-2026-53847.md) | Aug 11, 2026 |
| Linux | isns-utils rocky 10 | 0:0.103-1.el10_2.1 | [RLSA-2026:53846](https://patchblox.com/security/data/fix/linux/rlsa-2026-53846.md) | Aug 12, 2026 |
| Linux | isns-utils rocky 8 | 0:0.99-1.el8_10.1 | [RLSA-2026:53848](https://patchblox.com/security/data/fix/linux/rlsa-2026-53848.md) | Aug 12, 2026 |
| Linux | isns-utils rocky 9 | 0:0.101-4.el9_8.1 | [RLSA-2026:53847](https://patchblox.com/security/data/fix/linux/rlsa-2026-53847.md) | Aug 12, 2026 |
| Linux | isns-utils-debuginfo amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | isns-utils-debugsource amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | isns-utils-devel RHEL 8 | 0:0.99-1.el8_10.1 | [RHSA-2026:53848](https://patchblox.com/security/data/fix/linux/rhsa-2026-53848.md) | Aug 13, 2026 |
| Linux | isns-utils-devel almalinux 8 | 0.99-1.el8_10.1 | [ALSA-2026:53848](https://patchblox.com/security/data/fix/linux/alsa-2026-53848.md) | Aug 11, 2026 |
| Linux | isns-utils-devel amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | isns-utils-devel ol 8 | 0:0.99-1.el8_10.1 | [ELSA-2026-53848](https://patchblox.com/security/data/fix/linux/elsa-2026-53848.md) | Aug 12, 2026 |
| Linux | isns-utils-libs RHEL 8 | 0:0.99-1.el8_10.1 | [RHSA-2026:53848](https://patchblox.com/security/data/fix/linux/rhsa-2026-53848.md) | Aug 13, 2026 |
| Linux | isns-utils-libs RHEL 9 | 0:0.101-4.el9_8.1 | [RHSA-2026:53847](https://patchblox.com/security/data/fix/linux/rhsa-2026-53847.md) | Aug 13, 2026 |
| Linux | isns-utils-libs almalinux 10 | 0.103-1.el10_2.1 | [ALSA-2026:53846](https://patchblox.com/security/data/fix/linux/alsa-2026-53846.md) | Aug 11, 2026 |
| Linux | isns-utils-libs almalinux 8 | 0.99-1.el8_10.1 | [ALSA-2026:53848](https://patchblox.com/security/data/fix/linux/alsa-2026-53848.md) | Aug 11, 2026 |
| Linux | isns-utils-libs almalinux 9 | 0.101-4.el9_8.1 | [ALSA-2026:53847](https://patchblox.com/security/data/fix/linux/alsa-2026-53847.md) | Aug 11, 2026 |
| Linux | isns-utils-libs amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | isns-utils-libs ol 10 | 0:0.103-1.el10_2.1 | [ELSA-2026-53846](https://patchblox.com/security/data/fix/linux/elsa-2026-53846.md) | Aug 11, 2026 |
| Linux | isns-utils-libs ol 8 | 0:0.99-1.el8_10.1 | [ELSA-2026-53848](https://patchblox.com/security/data/fix/linux/elsa-2026-53848.md) | Aug 12, 2026 |
| Linux | isns-utils-libs ol 9 | 0:0.101-4.el9_8.1 | [ELSA-2026-53847](https://patchblox.com/security/data/fix/linux/elsa-2026-53847.md) | Aug 11, 2026 |
| Linux | isns-utils-libs-debuginfo amzn 2023 | 0.101-6.amzn2023.0.1 | [ALAS2023-2026-2054](https://patchblox.com/security/data/fix/linux/alas2023-2026-2054.md) | Aug 17, 2026 |
| Linux | libisns0 Ubuntu 18.04.6 LTS (bionic) | 0.97-2ubuntu0.1~esm1 | [libisns0 0.97-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libisns0-0.97-2ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | libisns0 Ubuntu 20.04 LTS (focal) | 0.97-3ubuntu0.1~esm1 | [libisns0 0.97-3ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libisns0-0.97-3ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | libisns0 Ubuntu 22.04.1 LTS (jammy) | 0.101-0ubuntu2.1 | [libisns0 0.101-0ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libisns0-0.101-0ubuntu2.1.md) | Jul 29, 2026 |
| Linux | libisns0t64 Ubuntu 24.04.5 LTS (noble) | 0.101-0.3ubuntu0.1 | [libisns0t64 0.101-0.3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libisns0t64-0.101-0.3ubuntu0.1.md) | Jul 29, 2026 |
| Linux | libisns0t64 Ubuntu 26.04.1 LTS (resolute) | 0.101-2.1ubuntu0.1 | [libisns0t64 0.101-2.1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-libisns0t64-0.101-2.1ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns Debian 14 | 0.103-2 | [DEBIAN-CVE-2026-55995](https://patchblox.com/security/data/fix/linux/debian-cve-2026-55995.md) | Aug 4, 2026 |
| Linux | open-isns-discoveryd Ubuntu 18.04.6 LTS (bionic) | 0.97-2ubuntu0.1~esm1 | [open-isns-discoveryd 0.97-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-open-isns-discoveryd-0.97-2ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-discoveryd Ubuntu 20.04 LTS (focal) | 0.97-3ubuntu0.1~esm1 | [open-isns-discoveryd 0.97-3ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-open-isns-discoveryd-0.97-3ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-discoveryd Ubuntu 22.04.1 LTS (jammy) | 0.101-0ubuntu2.1 | [open-isns-discoveryd 0.101-0ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-open-isns-discoveryd-0.101-0ubuntu2.1.md) | Jul 29, 2026 |
| Linux | open-isns-discoveryd Ubuntu 24.04.5 LTS (noble) | 0.101-0.3ubuntu0.1 | [open-isns-discoveryd 0.101-0.3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-open-isns-discoveryd-0.101-0.3ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns-discoveryd Ubuntu 26.04.1 LTS (resolute) | 0.101-2.1ubuntu0.1 | [open-isns-discoveryd 0.101-2.1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-open-isns-discoveryd-0.101-2.1ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns-server Ubuntu 18.04.6 LTS (bionic) | 0.97-2ubuntu0.1~esm1 | [open-isns-server 0.97-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-open-isns-server-0.97-2ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-server Ubuntu 20.04 LTS (focal) | 0.97-3ubuntu0.1~esm1 | [open-isns-server 0.97-3ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-open-isns-server-0.97-3ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-server Ubuntu 22.04.1 LTS (jammy) | 0.101-0ubuntu2.1 | [open-isns-server 0.101-0ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-open-isns-server-0.101-0ubuntu2.1.md) | Jul 29, 2026 |
| Linux | open-isns-server Ubuntu 24.04.5 LTS (noble) | 0.101-0.3ubuntu0.1 | [open-isns-server 0.101-0.3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-open-isns-server-0.101-0.3ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns-server Ubuntu 26.04.1 LTS (resolute) | 0.101-2.1ubuntu0.1 | [open-isns-server 0.101-2.1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-open-isns-server-0.101-2.1ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns-utils Ubuntu 18.04.6 LTS (bionic) | 0.97-2ubuntu0.1~esm1 | [open-isns-utils 0.97-2ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-open-isns-utils-0.97-2ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-utils Ubuntu 20.04 LTS (focal) | 0.97-3ubuntu0.1~esm1 | [open-isns-utils 0.97-3ubuntu0.1~esm1](https://patchblox.com/security/data/fix/linux/ubuntu-focal-open-isns-utils-0.97-3ubuntu0.1-esm1.md) | Jul 29, 2026 |
| Linux | open-isns-utils Ubuntu 22.04.1 LTS (jammy) | 0.101-0ubuntu2.1 | [open-isns-utils 0.101-0ubuntu2.1](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-open-isns-utils-0.101-0ubuntu2.1.md) | Jul 29, 2026 |
| Linux | open-isns-utils Ubuntu 24.04.5 LTS (noble) | 0.101-0.3ubuntu0.1 | [open-isns-utils 0.101-0.3ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-noble-open-isns-utils-0.101-0.3ubuntu0.1.md) | Jul 29, 2026 |
| Linux | open-isns-utils Ubuntu 26.04.1 LTS (resolute) | 0.101-2.1ubuntu0.1 | [open-isns-utils 0.101-2.1ubuntu0.1](https://patchblox.com/security/data/fix/linux/ubuntu-resolute-open-isns-utils-0.101-2.1ubuntu0.1.md) | Jul 29, 2026 |

---

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