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CVE-2026-58051 (GCVE-0-2026-58051)

Vulnerability from cvelistv5 – Published: 2026-06-28 01:32 – Updated: 2026-06-29 12:50

Title

libssh2 - Free of Uninitialized Pointer in publickey List Cleanup

Summary

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.

Severity ?

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H

8.3 (High)


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

CWE

CWE-908 - Use of Uninitialized Resource

Assigner

VulnCheck

References

URL

Tags

	https://github.com/bikini/exploitarium/tree/main/…	exploitthird-party-advisory
	https://github.com/libssh2/libssh2/blob/master/sr…	product
	https://www.vulncheck.com/advisories/libssh2-free…	third-party-advisory

Impacted products

	Vendor	Product	Version
	libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver)

Credits

ashdfrkl

Show details on NVD website

JSON

To clipboard

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CVE-2026-58050 (GCVE-0-2026-58050)

Vulnerability from cvelistv5 – Published: 2026-06-28 01:32 – Updated: 2026-06-29 12:27

Title

libssh2 - Integer Overflow in publickey Subsystem Attribute Allocation

Summary

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.

Severity ?

7 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H

8.3 (High)


                        
                          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

CWE

CWE-190 - Integer Overflow or Wraparound

Assigner

VulnCheck

References

URL

Tags

	https://github.com/bikini/exploitarium/tree/main/…	exploitthird-party-advisory
	https://github.com/libssh2/libssh2/blob/master/sr…	product
	https://www.vulncheck.com/advisories/libssh2-inte…	third-party-advisory

Impacted products

	Vendor	Product	Version
	libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver)

Credits

ashdfrkl

Show details on NVD website

JSON

To clipboard

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CVE-2025-15661 (GCVE-0-2025-15661)

Vulnerability from cvelistv5 – Published: 2026-06-18 20:18 – Updated: 2026-06-23 16:13 X_Open Source

Title

libssh2 - Heap Buffer Over-read via sftp_symlink() in sftp.c

Summary

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.

Severity ?

8.3 (High)


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

6.5 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:N/A:H

CWE

CWE-125 - Out-of-bounds Read

Assigner

VulnCheck

References

URL

Tags

	https://github.com/libssh2/libssh2/pull/1705	issue-tracking
	https://github.com/libssh2/libssh2/pull/1717	issue-tracking
	https://github.com/libssh2/libssh2/commit/2dae302…	patch
	https://www.vulncheck.com/advisories/libssh2-heap…	third-party-advisory

Impacted products

	Vendor	Product	Version
	libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver) Unaffected: 2dae3024897e1898d389835151f4e9606227721d (git)

Credits

Joshua Rogers Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

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CVE-2026-55200 (GCVE-0-2026-55200)

Vulnerability from cvelistv5 – Published: 2026-06-17 19:03 – Updated: 2026-07-01 03:55 X_Open Source

Title

libssh2 - Out-of-Bounds Write via Unchecked packet_length in transport.c

Summary

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.

Severity ?

9.2 (Critical)


                        
                          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

8.1 (High)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

CWE

CWE-680 - Integer Overflow to Buffer Overflow

Assigner

VulnCheck

References

URL

Tags

	https://github.com/libssh2/libssh2/pull/2052	issue-tracking
	https://github.com/libssh2/libssh2/commit/97acf3d…	patch
	https://www.vulncheck.com/advisories/libssh2-out-…	third-party-advisory

Impacted products

	Vendor	Product	Version
	libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver) Unaffected: 7acf3dfda80c91c3a8c9f2372546301d4a1a7a8 (git)

Credits

Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

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CVE-2026-55199 (GCVE-0-2026-55199)

Vulnerability from cvelistv5 – Published: 2026-06-17 18:44 – Updated: 2026-06-18 15:31 X_Open Source

Title

libssh2 - Pre-Authentication DoS via SSH_MSG_EXT_INFO Handler

Summary

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.

Severity ?

8.2 (High)


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

5.9 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

CWE

CWE-835 - Loop with Unreachable Exit Condition ('Infinite Loop')

Assigner

VulnCheck

References

URL

Tags

	https://github.com/libssh2/libssh2/pull/1864	issue-tracking
	https://github.com/libssh2/libssh2/commit/1762685…	patch
	https://www.vulncheck.com/advisories/libssh2-pre-…	third-party-advisory

Impacted products

	Vendor	Product	Version
	libssh2	libssh2	Affected: 0 , ≤ 1.11.1 (semver) Unaffected: 17626857d20b3c9a1addfa45979dadcee1cd84a4 (git)

Credits

Tristan Madani (@TristanInSec)

Show details on NVD website

JSON

To clipboard

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Search criteria

5 vulnerabilities by libssh2

CVE-2026-58051 (GCVE-0-2026-58051)

CVE-2026-58050 (GCVE-0-2026-58050)

CVE-2025-15661 (GCVE-0-2025-15661)

CVE-2026-55200 (GCVE-0-2026-55200)

CVE-2026-55199 (GCVE-0-2026-55199)