Vulnerability · Published Jun 28, 2026 · Assigned by VulnCheck
CVE-2026-58050libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation
High 7.0
In plain English
A high-severity integer overflow in libssh2 from libssh2. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
libssh2 through 1.11.1 reads an attacker-controlled 32-bit attribute count from a publickey-subsystem response and uses it in the allocation num_attrs * sizeof(libssh2_publickey_attribute) without bounds checking, so on 32-bit platforms the multiplication overflows to an undersized buffer. A malicious SSH server can then drive the attribute-parsing loop to write past the allocation, causing a heap buffer overflow in a connecting libssh2 client.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.21 | libssh2 | 1.11.1-r3 | ALPINE-CVE-2026-58050 |
| Alpine:v3.22 | libssh2 | 1.11.1-r3 | ALPINE-CVE-2026-58050 |
| Alpine:v3.23 | libssh2 | 1.11.1-r4 | ALPINE-CVE-2026-58050 |
| Alpine:v3.24 | libssh2 | 1.11.1-r4 | ALPINE-CVE-2026-58050 |
| Debian:12 | libssh2 | 1.10.0-3+deb12u1 | DEBIAN-CVE-2026-58050 |
| Debian:13 | libssh2 | 1.11.1-1+deb13u2 | DEBIAN-CVE-2026-58050 |
| Debian:14 | libssh2 | 1.11.1-6 | DEBIAN-CVE-2026-58050 |
| Ubuntu:22.04:LTS | libssh2 | 1.10.0-3ubuntu0.1 | UBUNTU-CVE-2026-58050 |
| Ubuntu:22.04:LTS | libssh2 | 1.10.0-3ubuntu0.1 | USN-8799-1 |
| Ubuntu:24.04:LTS | libssh2 | 1.11.0-4.1ubuntu0.24.04.3 | UBUNTU-CVE-2026-58050 |
| Ubuntu:24.04:LTS | libssh2 | 1.11.0-4.1ubuntu0.24.04.3 | USN-8532-1 |
| Ubuntu:25.10 | libssh2 | no fix listed | UBUNTU-CVE-2026-58050 |
| Ubuntu:26.04:LTS | libssh2 | 1.11.1-1ubuntu0.26.04.3 | UBUNTU-CVE-2026-58050 |
| Ubuntu:26.04:LTS | libssh2 | 1.11.1-1ubuntu0.26.04.3 | USN-8532-1 |
Affected products (as reported)
Weakness: CWE-190 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
References
- Proof of Concept exploit, third-party-advisory
- src/publickey.c product
- VulnCheck Advisory: libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation third-party-advisory