CVE catalog
CVE-2023-51766
exim4: CVE-2023-51766
- Severity
- Medium · CVSS 5.3
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N - Published
- Source
- [NVD] · [CVE record]
- EPSS
- 1.10% · Oct 25, 2026
Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not.
Vulnerable and fixed packages
Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.
| Distribution | Package | Release | Version | Status |
|---|---|---|---|---|
| Debian | exim4 | sid | 4.100.1-4 | fixed |
| Debian | exim4 | forky | 4.100.1-4 | fixed |
| Debian | exim4 | trixie | 4.98.2-1+deb13u4 | fixed |
| Debian | exim4 | trixie-security | 4.98.2-1+deb13u5 | fixed |
| Debian | exim4 | bookworm | 4.96-15+deb12u10 | fixed |
| Debian | exim4 | bookworm-security | 4.96-15+deb12u10 | fixed |
| Ubuntu | exim4 | pro | 4.89-5ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu2 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu3 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu4 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.2 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.3 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.4 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.5 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.8 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.9 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm2 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm3 | fixed |
| Ubuntu | exim4 | 20.04 | 4.92.1-1ubuntu3 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.92.1-1ubuntu4 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93~RC2-1ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-9ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-11ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-12ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.5 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.6 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.7 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.8 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.9 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.10 | fixed |
| Ubuntu | exim4 | 22.04 | 4.94.2-7ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-2ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu1 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.1 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.3 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.4 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.5 | fixed |
| Ubuntu | exim4 | pro | 4.92.1-1ubuntu3 | vulnerable |
| Ubuntu | exim4 | pro | 4.92.1-1ubuntu4 | vulnerable |
| Ubuntu | exim4 | pro | 4.93~RC2-1ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-9ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-11ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-12ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.1 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.5 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.6 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.7 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.8 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.9 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.10 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.11 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.12 | vulnerable |
| Ubuntu | exim4 | pro | 4.93-13ubuntu1.12+esm1 | fixed |
| Ubuntu | exim4 | pro | 4.89-5ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu2 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu3 | vulnerable |
| Ubuntu | exim4 | pro | 4.89-9ubuntu4 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.2 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.3 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.4 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.5 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.8 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.9 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm1 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm2 | vulnerable |
| Ubuntu | exim4 | pro | 4.90.1-1ubuntu1.10+esm3 | fixed |
| Ubuntu | exim4 | 20.04 | 4.92.1-1ubuntu3 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.92.1-1ubuntu4 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93~RC2-1ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-9ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-11ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-12ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.1 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.5 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.6 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.7 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.8 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.9 | vulnerable |
| Ubuntu | exim4 | 20.04 | 4.93-13ubuntu1.10 | fixed |
| Ubuntu | exim4 | 22.04 | 4.94.2-7ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-2ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu1 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.1 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.2 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.3 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.4 | vulnerable |
| Ubuntu | exim4 | 22.04 | 4.95-4ubuntu2.5 | fixed |
| Opensuse | exim | tumbleweed | 4.97.1-1.1 | fixed |
Fixed-version evidence
| Distribution | Package | Type | Release | Fixed version | Urgency | Origin | Bugs |
|---|---|---|---|---|---|---|---|
| Debian | exim4 | source | sid | 4.97-3 | not yet assigned | Not reported | [1059387] |
| Debian | exim4 | source | forky | 4.97-3 | not yet assigned | Not reported | [1059387] |
| Debian | exim4 | source | trixie | 4.97-3 | not yet assigned | Not reported | [1059387] |
| Debian | exim4 | source | bookworm | 4.96-15+deb12u4 | not yet assigned | Not reported | [1059387] |
| Ubuntu | exim4 | deb | pro | 4.90.1-1ubuntu1.10+esm3 | Not reported | USN-6611-1 | Not reported |
| Ubuntu | exim4 | deb | 20.04 | 4.93-13ubuntu1.10 | Not reported | USN-6611-1 | Not reported |
| Ubuntu | exim4 | deb | 22.04 | 4.95-4ubuntu2.5 | Not reported | USN-6611-1 | Not reported |
| Ubuntu | exim4 | deb | pro | 4.93-13ubuntu1.12+esm1 | Not reported | USN-8382-1 | Not reported |
| Ubuntu | exim4 | deb | pro | 4.90.1-1ubuntu1.10+esm3 | Not reported | UBUNTU-CVE-2023-51766 | Not reported |
| Ubuntu | exim4 | deb | 20.04 | 4.93-13ubuntu1.10 | Not reported | UBUNTU-CVE-2023-51766 | Not reported |
| Ubuntu | exim4 | deb | 22.04 | 4.95-4ubuntu2.5 | Not reported | UBUNTU-CVE-2023-51766 | Not reported |
| Opensuse | exim | rpm | tumbleweed | 4.97.1-1.1 | Not reported | OPENSUSE-SU-2024:13543-1 | Not reported |
OpenFactory catalog packages
Matching against OpenFactory catalog package versions is in progress.
References
- [https://ftp.suse.com/pub/projects/security/csaf/opensuse-su-2024_0007-1.json]
- [https://osv.dev/vulnerability/DEBIAN-CVE-2023-51766]
- [https://osv.dev/vulnerability/DLA-3708-1]
- [https://osv.dev/vulnerability/DSA-5597-1]
- [https://osv.dev/vulnerability/UBUNTU-CVE-2023-51766]
- [https://osv.dev/vulnerability/USN-6611-1]
- [https://osv.dev/vulnerability/USN-8382-1]
- [https://osv.dev/vulnerability/openSUSE-SU-2024:13543-1]
- [https://security-tracker.debian.org/tracker/CVE-2023-51766]
- [https://security.access.redhat.com/data/csaf/v2/vex/2023/cve-2023-51766.json]
- [https://wid.cert-bund.de/.well-known/csaf/white/2026/wid-sec-w-2026-3076.json]
[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]