Vulnerability · Published May 30, 2026 · Assigned by mitre
CVE-2026-48840
Medium 5.3
In plain English
A medium-severity security flaw in Exim from Exim. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 18% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)5.3Medium
Exploit odds (30 days)0.3%top 81.6% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | exim | 4.98.4-r0 | ALPINE-CVE-2026-48840 |
| Alpine:v3.24 | exim | 4.98.4-r0 | ALPINE-CVE-2026-48840 |
| Debian:12 | exim4 | 4.96-15+deb12u10 | DEBIAN-CVE-2026-48840 |
| Debian:13 | exim4 | 4.98.2-1+deb13u3 | DEBIAN-CVE-2026-48840 |
| Debian:14 | exim4 | 4.99.3-2 | DEBIAN-CVE-2026-48840 |
| Ubuntu:22.04:LTS | exim4 | 4.95-4ubuntu2.9 | USN-8353-1 |
| Ubuntu:22.04:LTS | exim4 | 4.95-4ubuntu2.9 | UBUNTU-CVE-2026-48840 |
| Ubuntu:24.04:LTS | exim4 | 4.97-4ubuntu4.6 | USN-8353-1 |
| Ubuntu:24.04:LTS | exim4 | 4.97-4ubuntu4.6 | UBUNTU-CVE-2026-48840 |
| Ubuntu:25.10 | exim4 | 4.98.2-1ubuntu2.3 | USN-8353-1 |
| Ubuntu:25.10 | exim4 | 4.98.2-1ubuntu2.3 | UBUNTU-CVE-2026-48840 |
| Ubuntu:26.04:LTS | exim4 | 4.99.1-1ubuntu1.3 | UBUNTU-CVE-2026-48840 |
| Ubuntu:26.04:LTS | exim4 | 4.99.1-1ubuntu1.3 | USN-8353-1 |
Affected products (as reported)
Weakness: CWE-839 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N