HIGH CWE-680
CVE-2026-55200
libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c
8.1/ 10
CVSS 3.1
High severity
3.9%
EPSS exploit odds
Chance of exploitation in the next 30 days
Higher than 90% of all CVEs
Not listed
CISA KEV catalog
No confirmed in-the-wild exploitation on CISA's list, but a public proof of concept exists.
Timeline
- Published
- Jun 17, 2026
- Updated
- Nov 8, 2026
- First covered
- Jun 30, 2026
- Latest story
- 5 months ago
Summary
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.
CWE-680Integer Overflow to Buffer Overflow
Attack profile
Attack vectorNetwork
ComplexityHigh
PrivilegesNone
User interactionNone
ScopeUnchanged
ConfidentialityHigh
IntegrityHigh
AvailabilityHigh
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HAffected products
- libssh21.11.11c3f1b7da588f2652260285529ec3c1f1125eb4e to before 97acf3dfda80c91c3a8c9f2372546301d4a1a7a8