Summary
It was discovered that libssh2 incorrectly handled certain SFTP server
responses. A remote attacker controlling an SSH server could use this issue
to cause libssh2 to crash or possibly execute arbitrary code.
(CVE-2026-66032)
It was discovered that libssh2 incorrectly handled AES-GCM cipher
negotiation. A remote attacker controlling an SSH server could possibly use
this issue to cause libssh2 to crash, resulting in a denial of service.
(CVE-2026-66033)
It was discovered that libssh2 incorrectly handled Encrypt-then-MAC cipher
negotiation. A remote attacker controlling an SSH server could use this
issue to cause libssh2 to crash or possibly execute arbitrary code.
(CVE-2026-66035)
Fixed packages 2
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 24.04 LTS 24.04:LTS | libssh2 | 1.11.0-4.1ubuntu0.24.04.4 |
| Ubuntu · 26.04 LTS 26.04:LTS | libssh2 | 1.11.1-1ubuntu0.26.04.4 |
Vulnerabilities 3
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High 8.8
libssh2 Double-Free Heap Corruption via sftp_open()
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 …
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High 7.5
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 ssh2_cipher_crypt() function in src/openssl.c that allows a malicious SSH server to crash any connecting client by negotiating AES-GCM cipher…
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High 7.5
libssh2 Heap Buffer Overflow via ETM Cipher Negotiation
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 ci…