CVE-2025-4877

Libssh: write beyond bounds in binary to base64 conversion functions

Published Aug 20, 2025 CVSS 3.1 · 4.5 Medium EPSS < 1% KEV · Not listed
Description
There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption.
This issue affects only 32-bits builds of libssh.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4385-1 libssh security update
EUVD EUVD EUVD-2025-28257 There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption. This issue affects only 32-bits builds of libssh.
Ubuntu USN Ubuntu USN USN-7619-1 libssh vulnerabilities
Ubuntu USN Ubuntu USN USN-7696-1 libssh vulnerabilities
History
Type Values Removed Values Added
First Time appeared Redhat rhel Els
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/a:redhat:enterprise_linux:10
cpe:/a:redhat:enterprise_linux:8
cpe:/o:redhat:rhel_els:6
cpe:/o:redhat:rhel_els:7
Vendors & Products Redhat rhel Els
Type Values Removed Values Added
CPEs cpe:/o:redhat:rhivos:1
Vendors & Products Redhat rhivos
Type Values Removed Values Added
First Time appeared Redhat rhivos
CPEs cpe:/o:redhat:rhivos:1
Vendors & Products Redhat rhivos
Type Values Removed Values Added
CPEs cpe:/o:redhat:enterprise_linux:9 cpe:/a:redhat:enterprise_linux:9::appstream
cpe:/o:redhat:enterprise_linux:9::baseos
References
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description No description is available for this CVE. There's a vulnerability in the libssh package where when a libssh consumer passes in an unexpectedly large input buffer to ssh_get_fingerprint_hash() function. In such cases the bin_to_base64() function can experience an integer overflow leading to a memory under allocation, when that happens it's possible that the program perform out of bounds write leading to a heap corruption. This issue affects only 32-bits builds of libssh.
Title libssh: Write beyond bounds in binary to base64 conversion functions Libssh: write beyond bounds in binary to base64 conversion functions
First Time appeared Redhat
Redhat enterprise Linux
Redhat openshift
CPEs cpe:/a:redhat:openshift:4
cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
Redhat openshift
References
Type Values Removed Values Added
Description No description is available for this CVE.
Title libssh: Write beyond bounds in binary to base64 conversion functions
Weaknesses CWE-190
CWE-787
References
Metrics threat_severity

None

cvssV3_1

{'score': 4.5, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L'}

threat_severity

Moderate

Weaknesses

Sources

Status
PUBLISHED
Assigner
redhat
Published
Updated
Nov 5, 2026, 3:46 PM
Reserved
May 16, 2025, 10:23 PM
Status
Deferred
Published
Aug 20, 2025, 1:15 PM
Modified
Nov 5, 2026, 4:17 PM
Severity
Moderate
Public date
Jun 24, 2025, 12:00 AM