# CVE-2026-0966: Libssh: buffer underflow in ssh_get_hexa() on invalid input

CVE-2026-0966 is fixed in 7 products on 1 platform, first by RHSA-2026:18160, released February 10, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-0966
- Priority: High
- CVSS: 8.2 (Moderate)
- EPSS: 0.0060
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 10, 2026
- Weakness: Buffer Underwrite ('Buffer Underflow')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-0966

## Description

A flaw was found in libssh. The API function `ssh_get_hexa()` is vulnerable to a denial of service when processing zero-length input. This can be exploited remotely by an attacker during GSSAPI (Generic Security Service Application Program Interface) authentication if the server's logging verbosity is set to `SSH_LOG_PACKET (3)` or higher. Successful exploitation could lead to a self-Denial of Service of the per-connection daemon process.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | libssh Debian 12.15 (bookworm) | 0.10.6-0+deb12u3 | [DEBIAN-CVE-2026-0966](https://patchblox.com/security/data/fix/linux/debian-cve-2026-0966.md) | Mar 26, 2026 |
| Linux | libssh Debian 13.5 (trixie) | 0.11.5-0+deb13u1 | [DEBIAN-CVE-2026-0966](https://patchblox.com/security/data/fix/linux/debian-cve-2026-0966.md) | Mar 26, 2026 |
| Linux | libssh Debian 14 | 0.12.0-1 | [DEBIAN-CVE-2026-0966](https://patchblox.com/security/data/fix/linux/debian-cve-2026-0966.md) | Mar 26, 2026 |
| Linux | libssh RHEL 10 | 0.12.0-2.el10 | [RHSA-2026:18160](https://patchblox.com/security/data/fix/linux/rhsa-2026-18160.md) | Feb 10, 2026 |
| Linux | libssh RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 |
| Linux | libssh almalinux 10 | 0.12.0-2.el10 | [ALSA-2026:18160](https://patchblox.com/security/data/fix/linux/alsa-2026-18160.md) | May 19, 2026 |
| Linux | libssh almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 |
| Linux | libssh amzn 2023 | 0.10.6-1.amzn2023.0.4 | [ALAS2023-2026-1461](https://patchblox.com/security/data/fix/linux/alas2023-2026-1461.md) | Mar 2, 2026 |
| Linux | libssh ol 10 | 0:0.12.0-2.el10 | [ELSA-2026-18160](https://patchblox.com/security/data/fix/linux/elsa-2026-18160.md) | Jul 8, 2026 |
| Linux | libssh ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 |
| Linux | libssh opensuse-leap 15.6 | 0.9.8-150600.11.9.1 | [SUSE-SU-2026:0779-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0779-1.md) | Mar 3, 2026 |
| Linux | libssh rocky 10 | 0:0.12.0-2.el10 | [RLSA-2026:18160](https://patchblox.com/security/data/fix/linux/rlsa-2026-18160.md) | May 29, 2026 |
| Linux | libssh rocky 9 | 0:0.10.4-18.el9 | [RLSA-2026:18683](https://patchblox.com/security/data/fix/linux/rlsa-2026-18683.md) | May 28, 2026 |
| Linux | libssh sles 15.7 | 0.9.8-150600.11.9.1 | [SUSE-SU-2026:0779-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-0779-1.md) | Mar 3, 2026 |
| Linux | libssh-4 Ubuntu 18.04.6 LTS (bionic) | 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | [libssh-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm6.md) | Mar 12, 2026 |
| Linux | libssh-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | [libssh-4 0.9.3-2ubuntu2.5+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-4-0.9.3-2ubuntu2.5-esm3.md) | Mar 12, 2026 |
| Linux | libssh-4 Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.6 | [libssh-4 0.9.6-2ubuntu0.22.04.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-4-0.9.6-2ubuntu0.22.04.6.md) | Mar 12, 2026 |
| Linux | libssh-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | [libssh-4 0.10.6-2ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-4-0.10.6-2ubuntu0.3.md) | Mar 12, 2026 |
| Linux | libssh-4 Ubuntu 25.10 (questing) | 0.11.2-1ubuntu0.2 | [libssh-4 0.11.2-1ubuntu0.2](https://patchblox.com/security/data/fix/linux/ubuntu-questing-libssh-4-0.11.2-1ubuntu0.2.md) | Mar 12, 2026 |
| Linux | libssh-config RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 |
| Linux | libssh-config almalinux 10 | 0.12.0-2.el10 | [ALSA-2026:18160](https://patchblox.com/security/data/fix/linux/alsa-2026-18160.md) | May 19, 2026 |
| Linux | libssh-config almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 |
| Linux | libssh-config amzn 2023 | 0.10.6-1.amzn2023.0.4 | [ALAS2023-2026-1461](https://patchblox.com/security/data/fix/linux/alas2023-2026-1461.md) | Mar 2, 2026 |
| Linux | libssh-config ol 10 | 0:0.12.0-2.el10 | [ELSA-2026-18160](https://patchblox.com/security/data/fix/linux/elsa-2026-18160.md) | Jul 8, 2026 |
| Linux | libssh-config ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 |
| Linux | libssh-debuginfo amzn 2023 | 0.10.6-1.amzn2023.0.4 | [ALAS2023-2026-1461](https://patchblox.com/security/data/fix/linux/alas2023-2026-1461.md) | Mar 2, 2026 |
| Linux | libssh-debugsource amzn 2023 | 0.10.6-1.amzn2023.0.4 | [ALAS2023-2026-1461](https://patchblox.com/security/data/fix/linux/alas2023-2026-1461.md) | Mar 2, 2026 |
| Linux | libssh-devel RHEL 9 | 0:0.10.4-18.el9 | [RHSA-2026:18683](https://patchblox.com/security/data/fix/linux/rhsa-2026-18683.md) | May 27, 2026 |
| Linux | libssh-devel almalinux 10 | 0.12.0-2.el10 | [ALSA-2026:18160](https://patchblox.com/security/data/fix/linux/alsa-2026-18160.md) | May 19, 2026 |
| Linux | libssh-devel almalinux 9 | 0.10.4-18.el9 | [ALSA-2026:18683](https://patchblox.com/security/data/fix/linux/alsa-2026-18683.md) | May 19, 2026 |
| Linux | libssh-devel amzn 2023 | 0.10.6-1.amzn2023.0.4 | [ALAS2023-2026-1461](https://patchblox.com/security/data/fix/linux/alas2023-2026-1461.md) | Mar 2, 2026 |
| Linux | libssh-devel ol 10 | 0:0.12.0-2.el10 | [ELSA-2026-18160](https://patchblox.com/security/data/fix/linux/elsa-2026-18160.md) | Jul 8, 2026 |
| Linux | libssh-devel ol 9 | 0:0.10.4-18.el9 | [ELSA-2026-18683](https://patchblox.com/security/data/fix/linux/elsa-2026-18683.md) | Jun 12, 2026 |
| Linux | libssh-gcrypt-4 Ubuntu 18.04.6 LTS (bionic) | 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6 | [libssh-gcrypt-4 0.8.0~20170825.94fa1e38-1ubuntu0.7+esm6](https://patchblox.com/security/data/fix/linux/ubuntu-bionic-libssh-gcrypt-4-0.8.0-20170825.94fa1e38-1ubuntu0.7-esm6.md) | Mar 12, 2026 |
| Linux | libssh-gcrypt-4 Ubuntu 20.04 LTS (focal) | 0.9.3-2ubuntu2.5+esm3 | [libssh-gcrypt-4 0.9.3-2ubuntu2.5+esm3](https://patchblox.com/security/data/fix/linux/ubuntu-focal-libssh-gcrypt-4-0.9.3-2ubuntu2.5-esm3.md) | Mar 12, 2026 |
| Linux | libssh-gcrypt-4 Ubuntu 22.04.1 LTS (jammy) | 0.9.6-2ubuntu0.22.04.6 | [libssh-gcrypt-4 0.9.6-2ubuntu0.22.04.6](https://patchblox.com/security/data/fix/linux/ubuntu-jammy-libssh-gcrypt-4-0.9.6-2ubuntu0.22.04.6.md) | Mar 12, 2026 |
| Linux | libssh-gcrypt-4 Ubuntu 24.04.5 LTS (noble) | 0.10.6-2ubuntu0.3 | [libssh-gcrypt-4 0.10.6-2ubuntu0.3](https://patchblox.com/security/data/fix/linux/ubuntu-noble-libssh-gcrypt-4-0.10.6-2ubuntu0.3.md) | Mar 12, 2026 |

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Data as of 2026-11-09T01:18:40Z 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

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