by Kastro
Paper/Archive/CVE-2026-55200

CVE-2026-55200

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

EPSS 4%public exploitCVSS 9.2
critical.is priorityof 100
56
CVSS 9.2 (CNA)9.2 / 10 × 3027.6Not in CISA KEV+300.0EPSS percentile 90.2.902 × 2018.0Exploit: SSVC poc+1010.0SSVC exploitation: poc+100.0
Description · from the CVE record

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.

Affected

ProductAffectedFixed inSource
libssh21.11.1–CNA
libssh21c3f1b7da588f2652260285529ec3c1f1125eb4e – < 97acf3dfda80c91c3a8c9f2372546301d4a1a7a897acf3dfda80c91c3a8c9f2372546301d4a1a7a8CNA

Scores by source

VulnCheck (CNA)9.2CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
VulnCheck (CNA)8.1CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CISA ADPSSVCExploitation: poc · Automatable: no · Technical impact: total

References

refgithub.com/libssh2/libssh2/pull/2052patchgithub.com/libssh2/libssh2/commit/97acf3dfda80c91c3a8c9f2372546301d4a1a7a8writeupvulncheck.com/advisories/libssh2-out-of-bounds-write-via-unchecked-packet-length-in-transport-cexploitweb.archive.org/web/20260623211210/https://github.com/bikini/exploitarium/tree/main/libssh2-cve-2026-55200-poc