CVE-2026-66035
Gravedad CVSS v4.0:
ALTA
Tipo:
CWE-122
Desbordamiento de búfer basado en memoria dinámica (Heap)
Fecha de publicación:
24/07/2026
Última modificación:
25/07/2026
Descripción
*** Pendiente de traducción *** libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer overflow vulnerability that allows a malicious SSH server to corrupt heap metadata in any connecting client by sending a packet with a packet_length smaller than the cipher's block size during Encrypt-then-MAC cipher negotiation. In the fullpacket() function in src/transport.c, the ETM path allocates a buffer of packet_length bytes but copies blocksize minus one bytes via memcpy, causing an overflow that on 32-bit glibc writes attacker-controlled bytes into an adjacent chunk's SIZE field, enabling tcache bin confusion, overlapping live objects, and function pointer overwrite during the session handshake before authentication.
Impacto
Puntuación base 4.0
7.70
Gravedad 4.0
ALTA
Puntuación base 3.x
7.50
Gravedad 3.x
ALTA