CVE-2026-66033
Fixed in a distro release EPSS <1%CVSS 7.5
libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM ciphers during handshake. Attackers can exploit the underflow in the expression computing blocksize minus aadlen minus authentication tag length to trigger an out-of-bounds read and a memcpy call with a near-SIZE_MAX length argument, causing immediate process crash before any authentication occurs.
Products: libssh2
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| Alpine 3.21 | libssh2 | 1.11.1-r3 |
| Alpine 3.22 | libssh2 | 1.11.1-r3 |
| Alpine 3.23 | libssh2 | 1.11.1-r4 |
| Alpine 3.24 | libssh2 | 1.11.1-r4 |
| Amazon Linux 2023 | cargo-c | 0.10.21-1.amzn2023.0.1 |
| Chainguard | libssh2 | no fix |
| Chainguard | libssh2-dev | no fix |
| Chainguard | libssh2-doc | no fix |
| Debian 13 | libssh2 | 1.11.1-1+deb13u2 |
| Debian 14 | libssh2 | 1.11.1-5 |
| Red Hat hummingbird 1 | libssh2 | 0:1.11.1-10.2.hum1 |
| Red Hat hummingbird 1 | libssh2-devel | 0:1.11.1-10.2.hum1 |
| Red Hat hummingbird 1 | libssh2-docs | 0:1.11.1-10.2.hum1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | libssh2_org | 1.11.0-150000.4.35.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | libssh2_org | 1.11.0-150000.4.35.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Micro 5.3 | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Micro 5.4 | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Micro 5.5 | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Module for Basesystem 15 SP7 | libssh2_org | 1.11.0-150600.20.6.1 |
| SUSE Linux Enterprise Server 12 SP5-LTSS | libssh2_org | 1.11.0-29.18.1 |
| SUSE Linux Enterprise Server 15 SP4-LTSS | libssh2_org | 1.11.0-150000.4.35.1 |
| SUSE Linux Enterprise Server 15 SP4-LTSS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Server 15 SP5-LTSS | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Server 15 SP6-LTSS | libssh2_org | 1.11.0-150600.20.6.1 |
| SUSE Linux Enterprise Server 16.0 | libssh2_org | 1.11.1-160000.5.1 |
| SUSE Linux Enterprise Server LTSS Extended Security 12 SP5 | libssh2_org | 1.11.0-29.18.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | libssh2_org | 1.11.0-150200.9.8.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | libssh2_org | 1.11.0-150600.20.6.1 |
| SUSE Linux Enterprise Server for SAP applications 16.0 | libssh2_org | 1.11.1-160000.5.1 |
| SUSE Linux Micro 6.0 | libssh2_org | 1.11.0-4.1 |
| SUSE Linux Micro 6.1 | libssh2_org | 1.11.0-slfo.1.1_2.1 |
| SUSE Linux Micro 6.2 | libssh2_org | 1.11.1-160000.5.1 |
| Ubuntu 24.04 LTS | libssh2 | 1.11.0-4.1ubuntu0.24.04.4 |
| Ubuntu 26.04 LTS | libssh2 | 1.11.1-1ubuntu0.26.04.4 |
| Wolfi | libssh2 | no fix |
| Wolfi | libssh2-dev | no fix |
| Wolfi | libssh2-doc | no fix |
| openSUSE Leap 16.0 | libssh2_org | 1.11.1-160000.5.1 |
| openSUSE Tumbleweed | libssh2_org | 1.11.1-4.1 |