CVE-2026-58050

Published Jun 28, 2026

Last updated 2 days ago

CVSS high 8.3

Overview

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.
Source
disclosure@vulncheck.com
NVD status
Analyzed
Products
libssh2

Risk scores

CVSS 4.0

Type
Secondary
Base score
8.3
Impact score
-
Exploitability score
-
Vector string
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/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
Severity
HIGH

CVSS 3.1

Type
Primary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
HIGH

Weaknesses

disclosure@vulncheck.com
CWE-190

Social media

Hype score
Not currently trending

  1. libssh2の脆弱性CVE-2026-58050に対する概念実証（PoC）エクスプロイトが公開される libssh2 Vulnerability CVE-2026-58050 Gets Public PoC Exploit #DailyCyberSecurity (Jun 28) https://t.co/SxHMqm068O

    @foxbook

    29 Jun 2026

    183 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  2. 🚨High - libssh2 Multiple Memory Corruption Issues (CVE-2026-58050 & CVE-2026-58051) Two related vulnerabilities in libssh2 through 1.11.1: CVE-2026-58050: Integer overflow in publickey subsystem attribute allocation on 32-bit platforms allows heap buffer overflow.

    @UpwindMDR

    28 Jun 2026

    84 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

  3. CVE-2026-58050 Heap Buffer Overflow in libssh2 Through 1.11.1 via Integer Overflow https://t.co/JBzaHo34Ua

    @VulmonFeeds

    28 Jun 2026

    106 Impressions

    0 Retweets

    0 Likes

    0 Bookmarks

    0 Replies

    0 Quotes

Configurations

Related CVEs

  1. libssh2 through 1.11.1 grows its publickey list with SSH2_REALLOC but does not zero-initialize new entries before parsing populates them, so a parse failure reaching the cleanup path leaves libssh2_publickey_list_free operating on an uninitialized entry. A malicious SSH server offering the publickey subsystem can use a malformed response to make cleanup free an uninitialized, attacker-influenceable attrs pointer in a connecting libssh2 client.•CVE-2026-58051
  2. libssh2 through 1.11.1, fixed in commit 2dae302, contains an out-of-bounds heap read vulnerability in the sftp_symlink() function in src/sftp.c that allows a malicious SSH server or man-in-the-middle attacker to disclose heap memory contents or cause a crash by sending a crafted SSH_FXP_NAME response. Attackers can supply a link_len value larger than the actual packet data in SSH_FXP_NAME responses for SFTP READLINK and REALPATH operations, triggering a heap buffer over-read of up to target_len minus one bytes due to the missing validation of available packet buffer size before the memcpy operation.•CVE-2025-15661
  3. 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 achieve remote code execution.•CVE-2026-55200
  4. libssh2 through 1.11.1, fixed in commit 1762685, contains a pre-authentication denial of service vulnerability in the SSH_MSG_EXT_INFO handler in src/packet.c that allows a malicious SSH server to cause a client CPU exhaustion loop by sending a crafted extension count value. A malicious server can set nr_extensions to 0xFFFFFFFF during key exchange, causing the client to spin in a tight CPU loop for over 60 seconds because return values from _libssh2_get_string() are unchecked and the session timeout does not apply to CPU-bound loops.•CVE-2026-55199
  5. A security vulnerability has been detected in libssh2 up to 1.11.1. The impacted element is the function userauth_password of the file src/userauth.c. Such manipulation of the argument username_len/password_len leads to integer overflow. The attack may be launched remotely. The name of the patch is 256d04b60d80bf1190e96b0ad1e91b2174d744b1. A patch should be applied to remediate this issue.•CVE-2026-7598

References

Sources include official advisories and independent security research.