CVE-2026-66033: falha de alta gravidade em libssh2
libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation
Publicada em · Atualizada em
Aviso por e-mail quando ela entrar no KEV, ganhar PoC pública ou subir de nota.
21Vexday Risk Score
Sem sinal de exploração. Nenhum artefato público de exploração conhecido até agora.
ssvc Trackcvss 8.7epss 0.6%
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Produtos afetados
libssh2 · libssh2CVEs relacionadas — libssh2
No mesmo produto, das mais perigosas para as menos.
CVE-2026-55200CRITICALlibssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.cEPSS 3.9%CVE-2026-55199HIGHlibssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO HandlerEPSS 0.9%CVE-2025-15661HIGHlibssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.cEPSS 0.6%CVE-2026-66035HIGHlibssh2 Heap Buffer Overflow via ETM Cipher NegotiationEPSS 0.5%CVE-2026-66032HIGHlibssh2 Double-Free Heap Corruption via sftp_open()EPSS 0.4%CVE-2026-58050HIGHlibssh2 - Integer Overflow in publickey Subsystem Attribute AllocationEPSS 0.4%