Critical libssh2 Vulnerability Allows Attackers to Execute Remote Code Via Malicious SSH packets
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A critical security vulnerability has been identified in the widely used libssh2 library, allowing remote attackers to execute arbitrary code through specially crafted SSH packets.<\/p>\n
The flaw, tracked as CVE-2026-55200, carries a CVSS score of 9.2 and is classified under CWE-680 (Integer Overflow to Buffer Overflow<\/a>).<\/p>\n Disclosed on June 17, 2026, the vulnerability affects libssh2 versions 1.11.1 and earlier and was fixed in commit 7acf3df, with an official patch available through the project\u2019s GitHub repository.<\/p>\n The flaw resides in the ssh2_transport_read() function, which fails to validate the packet_length field in incoming SSH packets properly.<\/p>\n Due to missing upper-bound checks, attackers can supply excessively large values for packet_length, triggering an integer overflow that leads to an out-of-bounds heap write<\/a>.<\/p>\n This memory corruption condition allows attackers to overwrite adjacent memory structures, potentially enabling full remote code execution without authentication.<\/p>\n Because the attack vector is network-based and requires no user interaction, the risk of exploitation is considered high.<\/p>\n Successful exploitation of CVE-2026-55200 can result in remote code execution<\/a> on affected systems, allowing attackers to take control of vulnerable applications.<\/p>\n According to the VulnCheck advisory<\/a>, the flaw can cause heap memory corruption, leading to crashes, denial-of-service conditions, and potentially full system compromise on systems using libssh2 for secure communications.<\/p>\n The CVSS v4 vector reflects low attack complexity and high impact across confidentiality, integrity, and availability. Security researcher Tristan Madani responsibly disclosed the vulnerability, enabling a coordinated fix before widespread exploitation. The issue affects all applications and systems using libssh2 versions 1.11.1 and earlier.<\/p>\n Since libssh2 is widely embedded in SSH clients<\/a>, automation frameworks, and file transfer tools, the exposure extends across enterprise environments, cloud services, and embedded systems.<\/p>\n The issue has been addressed in a patch introduced by commit 97acf3dfda80c91c3a8c9f2372546301d4a1a7a8, which enforces strict validation of packet_length values to prevent integer and buffer overflows.<\/p>\n Organizations are strongly encouraged to upgrade libssh2 to a patched version as soon as possible.<\/p>\n In addition, security teams should review systems for statically linked or bundled versions of libssh2, monitor SSH traffic for anomalies such as unusually large packet sizes, and implement network-level controls if immediate patching is not feasible.<\/p>\n Follow us on\u00a0Google News<\/a>,\u00a0LinkedIn<\/a>,\u00a0and\u00a0X<\/a>\u00a0to Get More Instant Updates.<\/strong><\/p>\n The post Critical libssh2 Vulnerability Allows Attackers to Execute Remote Code Via Malicious SSH packets<\/a> appeared first on Cyber Security News<\/a>.<\/p>\n<\/div>\nlibssh2 Vulnerability<\/strong><\/h2>\n