CVE-2026-66033

Name
CVE-2026-66033
Description
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.
NVD Severity
unknown
Other trackers
CVE, NVD, CERT, CVE Details, CIRCL, Arch Linux, Debian, Red Hat, Ubuntu, Gentoo, SUSE (Bugzilla), SUSE (CVE), Mageia
Mailing lists
oss-security, full-disclosure, bugtraq
Exploits
Exploit DB, Metasploit
Forges
GitHub (code, issues), Aports (code, issues)

References

Type URI
disclosure@vulncheck.com https://github.com/libssh2/libssh2/commit/a2ed82d40964bbc0d64cd717aa0a5a892117d2e6
disclosure@vulncheck.com https://github.com/libssh2/libssh2/pull/2401
disclosure@vulncheck.com https://www.vulncheck.com/advisories/libssh2-integer-underflow-dos-via-aes-gcm-cipher-negotiation

Match rules

CPE URI Source package Min version Max version
cpe:2.3:a:libssh2:libssh2:*:*:*:*:*:*:*:* libssh2 >= None <= 1.11.1

Vulnerable and fixed packages

Source package Branch Version Maintainer Status
libssh2 edge-main 1.11.1-r3 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.11.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.11.1-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.11.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.11.0-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.9.0-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.9.0-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 edge-main 1.9.0-r0 None possibly vulnerable
libssh2 edge-main 1.8.1-r0 None possibly vulnerable
libssh2 3.24-main 1.11.1-r3 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.24-main 1.11.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.23-main 1.11.1-r3 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.23-main 1.11.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.23-main 1.11.1-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.22-main 1.11.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.22-main 1.11.1-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.22-main 1.11.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.22-main 1.11.0-r1 None possibly vulnerable
libssh2 3.22-main 1.9.0-r1 None possibly vulnerable
libssh2 3.22-main 1.9.0-r0 None possibly vulnerable
libssh2 3.22-main 1.8.1-r0 None possibly vulnerable
libssh2 3.21-main 1.11.1-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.21-main 1.11.1-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.21-main 1.11.1-r0 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.21-main 1.11.0-r1 None possibly vulnerable
libssh2 3.21-main 1.9.0-r1 None possibly vulnerable
libssh2 3.21-main 1.9.0-r0 None possibly vulnerable
libssh2 3.21-main 1.8.1-r0 None possibly vulnerable
libssh2 3.20-main 1.11.0-r3 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.20-main 1.11.0-r2 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.20-main 1.11.0-r1 None possibly vulnerable
libssh2 3.20-main 1.9.0-r1 None possibly vulnerable
libssh2 3.20-main 1.9.0-r0 None possibly vulnerable
libssh2 3.20-main 1.8.1-r0 None possibly vulnerable
libssh2 3.19-main 1.11.0-r1 Natanael Copa <ncopa@alpinelinux.org> possibly vulnerable
libssh2 3.19-main 1.9.0-r1 None possibly vulnerable
libssh2 3.19-main 1.9.0-r0 None possibly vulnerable
libssh2 3.19-main 1.8.1-r0 None possibly vulnerable