CVE-2026-66033

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66033 libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66033 libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66033 libssh2 Integer Underflow DoS via AES-GCM Cipher Negotiation

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66033

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66033

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66032

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

CVE-2026-66032

libssh2

CVE-2026-66032 libssh2 Double-Free Heap Corruption via sftp_open()

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

CVE-2026-66032 libssh2 Double-Free Heap Corruption via sftp_open()

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

CVE-2026-66032

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

EUVD-2026-48719

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

CVE-2026-66032

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

PT-2026-64382

Name of the Vulnerable Software and Affected Versions libssh2 versions prior to 1.11.1 Description A pre-authentication heap buffer overflow occurs during Encrypt-then-MAC ETM cipher negotiation. A malicious SSH server can corrupt heap metadata in a connecting client by sending a packet where the...

CVE-2026-66034: Out-of-bounds Read

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 libssh2publickeylistfetch, the version 1...

CVE-2026-66035: Heap-based Buffer Overflow

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 packetlength smaller than the cipher's block size during Encrypt-then-M...

CVE-2026-66033: Integer Underflow (Wrap or Wraparound)

libssh2 through 1.11.1, fixed in commit a2ed82d, contains a pre-authentication integer underflow vulnerability in the ssh2ciphercrypt 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...

CVE-2026-66032: Double Free

libssh2 through 1.11.1, fixed in commit 5e47761, contains a double-free vulnerability in the sftpopen 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 SSHFXPOPEN with SSHFXPSTATUS containin...

PT-2026-64380

Name of the Vulnerable Software and Affected Versions libssh2 versions prior to 1.11.1 Description A pre-authentication integer underflow exists in the ssh2 cipher crypt function within src/openssl.c. A malicious SSH server can trigger this issue during the handshake by negotiating AES-GCM cipher...

PT-2026-64379

Name of the Vulnerable Software and Affected Versions libssh2 versions prior to 1.11.1 Description A double-free issue exists in the sftp open function within src/sftp.c. This occurs when a malicious SSH server responds to SSH FXP OPEN with SSH FXP STATUS containing FX OK, causing the response da...