---
title: "CVE-2026-48840\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-2026-48840?format=md
keywords: index, follow
---

# CVE-2026-48840

Publication date 29 May 2026

Last updated 6 June 2026

---

Ubuntu priority

**Medium**

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

## Cvss 3 Severity Score

**5.3 · Medium**

[Score breakdown](https://ubuntu.com/security/CVE-2026-48840?format=md#impact-score)

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## Description

Exim 4.88 before 4.99.4, in some proxy configurations, mishandles certain
short payloads, leading to disclosure of uninitialized stack memory values
to a client.

[Read the notes from the security team](https://ubuntu.com/security/CVE-2026-48840?format=md#notes)

## Status

Show unmaintained releases

| Package | Ubuntu Release | Status |
| --- | --- | --- |
| exim4 | 26.04 LTS resolute | Fixed 4.99.1-1ubuntu1.3 |
| 25.10 questing | Fixed 4.98.2-1ubuntu2.3 |
| 24.04 LTS noble | Fixed 4.97-4ubuntu4.6 |
| 22.04 LTS jammy | Fixed 4.95-4ubuntu2.9 |
| 20.04 LTS focal | Fixed 4.93-13ubuntu1.12+esm1  Ubuntu Pro |
| 18.04 LTS bionic | Fixed 4.90.1-1ubuntu1.10+esm6  Ubuntu Pro |
| 16.04 LTS xenial | Fixed 4.86.2-2ubuntu2.6+esm9  Ubuntu Pro |
| 14.04 LTS trusty | Not affected |

---

* [How can I get the fixes?](https://ubuntu.com/security/cves/about#security)
* [What do statuses mean?](https://ubuntu.com/security/cves/about#statuses)

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## Notes

---

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

This is EXIM-Security-2026-05-19.1

## Severity score breakdown

CVSS version:
CVSS v3.0

**Base score**

5.3 · Medium

* Base metrics

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

  | Parameter | Value |
  | --- | --- |
  | Base score | 5.3 · Medium |
  | Exploitability score | - |
  | Impact score | - |

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

## References

* [MITRE](https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2026-48840)
* [NVD](https://nvd.nist.gov/vuln/detail/CVE-2026-48840)
* [Launchpad](https://launchpad.net/bugs/cve/CVE-2026-48840)
* [Debian](https://security-tracker.debian.org/tracker/CVE-2026-48840)

### Related Ubuntu Security Notices (USN)

+ [USN-8353-1](https://usn.ubuntu.com/USN-8353-1)
+ Exim vulnerability
+ 1 June 2026

+ [USN-8382-1](https://usn.ubuntu.com/USN-8382-1)
+ Exim vulnerabilities
+ 3 June 2026

### Other references

* <https://www.cve.org/CVERecord?id=CVE-2026-48840>
* <https://www.exim.org/static/doc/security/EXIM-Security-2026-05-19.1/EXIM-Security-2026-05-19.1.txt>