CVE-2026-55200criticalCWE-680

CVE-2026-55200: critical vulnerability in libssh2

libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c

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48Vexday Risk Score

No sign of exploitation. It has a public proof of concept.

ssvc Attendcvss 9.2epss 3.9%
from disclosure to weapon6 days
Published on NVDJun 17
1st PoC+6d
libssh2 1.11.1, fixed in commit 97acf3d, contains an out-of-bounds write vulnerability in ssh2_transport_read() that fails to enforce upper bounds on packet_length field. Remote attackers can send crafted SSH packets with excessively large packet_length values to corrupt heap memory and achieve remote code execution.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
libssh2 · libssh2
⚠ Public resources, to assess the exposure of systems you control or are authorized to test. Test only with authorization.
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