Cyber Resilience

CVE-2026-55200

CriticalPublic PoCUpdated

Published: 17 June 2026

Published
17 June 2026
Modified
01 July 2026
KEV Added
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Patch
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CVSS Score v4 9.2 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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS Score 0.0073 49.8th percentile
Risk Priority 70 floored blend · peak EPSS

Summary

CVE-2026-55200 is a critical-severity Integer Overflow to Buffer Overflow (CWE-680) vulnerability in Libssh2 Libssh2. Its CVSS base score is 9.2 (Critical).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 49.8th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.

EU & UK References

Vulnerability details

libssh2 through 1.11.1, fixed in commit 7acf3df 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…

more

achieve remote code execution.

CWE(s)
CWE-680

Related Threats

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access
Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.
attack.mitre.org →
Why these techniques?

Out-of-bounds write in libssh2 SSH transport enables remote attackers to achieve RCE via crafted packets against a public-facing SSH service.

Confidence: HIGH · MITRE ATT&CK Enterprise v19.0

Affected Assets

libssh2
libssh2
≤ 1.11.1

Mitigating Controls

No mitigating controls mapped yet. The per-CVE control annotator has not reached this CVE.

References