Integer overflow in Libssh

CVE-2025-5449

A flaw was found in the SFTP server message decoding logic of libssh. The issue occurs due to an incorrect packet length check that allows an integer overflow when handling large payload sizes on 32-bit systems. This issue leads to failed memory allocation and causes the server process to crash, resulting in a denial of service.

Vulnerability class: Integer Overflow

EPSS: 0.008 (52.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

Public proof-of-concept exploits

References

Frequently asked questions

What is CVE-2025-5449?
CVE-2025-5449 is a medium-severity vulnerability in Libssh, classified under Integer Overflow or Wraparound. CVSS score: 6.5/10. Published 2025-07-25.
How severe is CVE-2025-5449?
Medium severity. CVSS v3 base score is 6.5 out of 10.
Is CVE-2025-5449 known to be exploited?
1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.