CVE-2026-66034 – libssh2 Heap Out-of-Bounds Read via publickey subsystem

CVE ID :CVE-2026-66034

Published : July 24, 2026, 5:17 p.m. | 32 minutes ago

Description :libssh2 through 1.11.1, fixed in commit a13bb6c, contains a missing bounds check vulnerability that allows a malicious SSH server to trigger an arbitrary-length heap out-of-bounds read and a free of an uninitialized pointer via the publickey subsystem. In libssh2_publickey_list_fetch(), the version 1 response parser reads a server-controlled comment_len value and advances the parse pointer without verifying sufficient bytes remain in the buffer, causing the out-of-bounds read to leak heap pointers from adjacent allocations defeating ASLR, followed by heap allocator state corruption when the error cleanup path frees an uninitialized pointer from a non-zeroed realloc() region.

Severity: 7.7 | HIGH

Visit the link for more details, such as CVSS details, affected products, timeline, and more…