Astra Linux – Vulnerabilities in paramiko, libssh, libssh2, erlang, openssh

The SSH transport protocol, with certain OpenSSH extensions, found in OpenSSH versions prior to 9.6 and other products, allows remote attackers to bypass integrity checks. As a result, some packets may be omitted from the extension negotiation message. Consequently, the client and server may end ...

JLSEC-2026-1088 libssh2 through 1.11.1, fixed in commit 42e33d8, contains a pre-authentication heap buffer...

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...

erlang -- SSH plaintext recovery attack against CBC ciphers

The Erlang/OTP team reports: The SSH client and server now reject incoming packets not aligned to the cipher block size as required by RFC 4253 section 6. For CBC ciphers, a timing-safe "packet discard" mechanism CVE-2008-5161 mitigation ensures structural errors are indistinguishable from MAC...

SUSE CVE-2026-66035

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-2026-66035

A flaw was found in libssh2. A malicious SSH server can exploit a pre-authentication heap buffer overflow vulnerability by sending a specially crafted packet during the Encrypt-then-MAC ETM cipher negotiation. This allows the server to corrupt heap memory, potentially leading to arbitrary code...

libssh2 Heap Buffer Overflow via ETM Cipher Negotiation

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Heap-based Buffer Overflow

Overview Affected versions of this package are vulnerable to Heap-based Buffer Overflow in the fullpacket function during Encrypt-then-MAC cipher negotiation. An attacker can corrupt heap metadata and potentially achieve arbitrary code execution or cause a denial of service by sending a specially...

AZL-93399 CVE-2026-66035 affecting package libssh2 for versions less than 1.11.1-5

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-2026-66035

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...

UBUNTU-CVE-2026-66035

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-2026-66035 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 packetlength smaller than the cipher's block size during Encrypt-then-M...

EUVD-2026-48722

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-2026-66035 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 packetlength smaller than the cipher's block size during Encrypt-then-M...

CVE-2026-66035

CVE-2026-66035 affects libssh2 up to 1.11.1 and was fixed in commit 42e33d8. The vulnerability is a pre-authentication heap buffer overflow in the Encrypt-then-MAC (ETM) cipher negotiation path. In libssh2’s fullpacket() implemented under src/transport.c, the ETM code path allocates a buffer of p...

CVE-2026-66035 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 packetlength smaller than the cipher's block size during Encrypt-then-M...

CVE-2026-66035

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-2026-66035

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...

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-2026-66035: 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...

Prefix Truncation Attack against ChaCha20-Poly1305 and Encrypt-then-MAC aka Terrapin

SummaryTerrapin is a prefix truncation attack targeting the SSH protocol. More precisely, Terrapin breaks the integrity of SSH's secure channel. By carefully adjusting the sequence numbers during the handshake, an attacker can remove an arbitrary amount of messages sent by the client or server at...