---
title: "CVE-2023-3603\n    | Ubuntu"
description: Ubuntu is an open source software operating system that runs from the
  desktop, to the cloud, to all your internet connected things.
url: https://ubuntu.com/security/CVE-2023-3603?format=md
keywords: index, follow
---

# CVE-2023-3603

Publication date 21 July 2023

Last updated 4 August 2025

---

Ubuntu priority

**Medium**

[Why this priority?](https://ubuntu.com/security/cves/about#priority )

## Cvss 3 Severity Score

**6.5 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2023-3603?format=md#impact-score)

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## Description

A missing allocation check in sftp server processing read requests may
cause a NULL dereference on low-memory conditions. The malicious client can
request up to 4GB SFTP reads, causing allocation of up to 4GB buffers,
which was not being checked for failure. This will likely crash the
authenticated user's sftp server connection (if implemented as forking as
recommended). For thread-based servers, this might also cause DoS for
legitimate users.
Given this code is not in any released versions, no security releases have
been issued.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2023-3603?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| libssh | 23.04 lunar | Not affected |
| 22.10 kinetic | Not affected |
| 22.04 LTS jammy | Not affected |
| 20.04 LTS focal | Not affected |
| 18.04 LTS bionic | Not affected |
| 16.04 LTS xenial | Not affected |
| 14.04 LTS trusty | Ignored end of standard support |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)
* [Patch details](https://ubuntu.com/security/CVE-2023-3603?format=md#patch-details)

## Notes

---

### [mdeslaur](https://launchpad.net/~mdeslaur)

code is not present in any released version

### Patch details

For informational purposes only. We recommend not to cherry-pick updates. [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)

| Package | Patch details |
| --- | --- |
| libssh | * Upstream:   [?id=fe8](https://git.libssh.org/projects/libssh.git/commit/?id=fe80f47b0ae8902d229ef9b8a1b4fa949b92e720) |

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

6.5 · Medium

* Base metrics

  | Parameter | Value |
  | --- | --- |
  | Attack vector | Network |
  | Attack complexity | Low |
  | Privileges required | Low |
  | User interaction | None |
  | Scope | Unchanged |
  | Confidentiality impact | None |
  | Integrity impact | None |
  | Availability impact | High |
* Scores

  | Parameter | Value |
  | --- | --- |
  | Base score | 6.5 · Medium |
  | Exploitability score | - |
  | Impact score | - |

**Vector:** CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-3603)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2023-3603)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2023-3603)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2023-3603)

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2023-3603>