SB2025082012 - Ubuntu update for libssh

Description

This security bulletin contains information about 3 vulnerabilities.

1) Integer overflow (CVE-ID: CVE-2025-4877)

CWE-ID: CWE-190 - Integer overflow

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to execute arbitrary code on the target system.

The vulnerability exists due to integer overflow within the bin_to_base64() function in base64.c. A local user can trigger an integer overflow and execute arbitrary code on the target system.

Note, the vulnerability can be exploited only via the ssh_get_fingerprint_hash() function on 32-bit builds in case the API is (mis)used and a libssh consumer passes in an unexpectedly large input buffer.

2) Use-after-free (CVE-ID: CVE-2025-4878)

CWE-ID: CWE-416 - Use After Free

CVSSv4: CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:U/U:Clear

The vulnerability allows a local user to escalate privileges on the system.

The vulnerability exists due to a use-after-free error within the privatekey_from_file() function. A local user can trigger a use-after-free error and execute arbitrary code with elevated privileges. 

3) Out-of-bounds read (CVE-ID: CVE-2025-5318)

CWE-ID: CWE-125 - Out-of-bounds read

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to gain access to potentially sensitive information.

The vulnerability exists due to a boundary condition within the sftp_handle() function. A remote user can trigger an out-of-bounds read error and read contents of memory on the system.

Remediation

Install update from vendor's website.

References

• https://ubuntu.com/security/notices/USN-7696-1