Description
Exim before 4.100.1, when Proxy-Protocol is used with an attacker-controlled proxy, has an out-of-bounds write.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Exim | Exim | 4.83 – < 4.100.1 | 4.100.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | exim4 | 4.100.1-1 | — |
| Debian 13 | exim4 | 4.98.2-1+deb13u5 | — |
| Debian 12 | exim4 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | exim4 | 4.99.1-1ubuntu1.5 | USN-8834-1 |
| Ubuntu 24.04 LTS | exim4 | 4.97-4ubuntu4.8 | USN-8834-1 |
| Ubuntu 22.04 LTS | exim4 | 4.95-4ubuntu2.12 | USN-8834-1 |
Show 4 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | exim4 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | exim4 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | exim4 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | exim4 | No fix yet | — |
Advisories 2
- WID-SEC-2026-3475 Exim: Mehrere Schwachstellen BSI CERT-Bund (WID) · Oct 6, 2026
- USN-8834-1 exim4 vulnerabilities Ubuntu Security Notices (USN) · Sep 28, 2026