CVE-2025-5449: Libssh: integer overflow in libssh sftp server packet length validation leading to denial of service

Severity: medium (CVSS 6.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.0% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-07-25 · updated 2026-08-31
Weakness: CWE-190

Description

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.

Affected products

libssh: 0.11.0, 0.11.1

References

https://access.redhat.com/security/cve/CVE-2025-5449
https://bugzilla.redhat.com/show_bug.cgi?id=2369705
https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=261612179f740bc62ba363d98b3bd5e5573a811f
https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=3443aec90188d6aab9282afc80a81df5ab72c4da
https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=5504ff40515439a5fecbb17da7483000c4d12eb7
https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=78485f446af9b30e37eb8f177b81940710d54496
https://git.libssh.org/projects/libssh.git/commit/?h=stable-0.11&id=f79ec51b7fd519dbc5737a7ba826e3ed093f6ceb
https://www.libssh.org/security/advisories/CVE-2025-5449.txt

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