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libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftp_open() function in src/sftp.c that allows a malicious SSH server to corrupt the heap of any authenticated client opening an SFTP session. When a server responds to SSH_FXP_OPEN with SSH_FXP_STATUS containing FX_OK, the response data buffer is freed, and if a subsequent sftp_packet_require() call returns a specific error such as LIBSSH2_ERROR_CHANNEL_PACKET_EXCEEDED, the same pointer is freed a second time, enabling tcache dup conditions on glibc systems that allow overlapping allocations and function pointer overwrites.
I have seen this bug on a website I manage ( https://basketballbrosgame.org ). I’ve checked the affected libssh2 package and tried updating it to the latest available version, but I’m still seeing the SFTP problem. I’m not sure yet whether the website itself is directly affected or if it’s coming from the system package.
This issue has been addressed in the following products: Red Hat Enterprise Linux 7 Extended Lifecycle Support Via RHSA-2026:61752 https://access.redhat.com/errata/RHSA-2026:61752