Vulnerability record/PUBLISHED/Published Jun 17, 2026 19:03:15 UTC

CVE-2026-55200

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.

Base score9.2/ 10

SeverityCriticalCVSS 4.0

Exploitability / impact

CVSS metric breakdown

Vector-derived attributes

Base severityCritical

Attack vectorNetworkAV

Attack complexityLowAC

Attack requirementsPresentAT

Privileges requiredNonePR

User interactionNoneUI

Vulnerable system confidentialityHighVC

Vulnerable system integrityHighVI

Vulnerable system availabilityHighVA

Subsequent system confidentialityNoneSC

Subsequent system integrityNoneSI

Subsequent system availabilityNoneSA

CVSS vector stringCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS communicates standardized severity and impact characteristics. It does not establish whether a system is exploitable in your specific environment.

Record context

CVE Numbering AuthorityVulnCheck

Last updatedNov 8, 2026 14:05:21 UTC

PublishedJun 17, 2026 19:03:15 UTC

ReservedJun 16, 2026 15:53:37 UTC

Credits

Tristan Madani (@TristanInSec)