{"id":"AZL-93399","summary":"CVE-2026-66035 affecting package libssh2 for versions less than 1.11.1-5","details":"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.","modified":"2026-08-29T05:27:27Z","published":"2026-07-24T17:17:35Z","upstream":["CVE-2026-66035"],"references":[{"type":"WEB","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-66035"}],"affected":[{"package":{"name":"libssh2","ecosystem":"Azure Linux:3","purl":"pkg:rpm/azure-linux/libssh2"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.11.1-5"}]}],"database_specific":{"source":"https://github.com/microsoft/AzureLinuxVulnerabilityData/blob/main/osv/AZL-93399.json"}}],"schema_version":"1.9.0"}