Description
Exim SMTP Challenge Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Exim. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the handling of NTLM challenge requests. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the service account.
. Was ZDI-CAN-17515.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Exim | Exim | exim 4.95 | — |
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 | 4.97~RC1-2 | — |
| Debian 13 | exim4 | 4.97~RC1-2 | — |
| Debian 12 | exim4 | 4.96-15+deb12u2 | DSA-5512-1 |
| Debian 11 | exim4 | 4.94.2-7+deb11u1 | DSA-5512-1 |
| Debian 10 | exim4 | 4.92-8+deb10u8 | DLA-3599-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 22.04 LTS | exim4 | 4.95-4ubuntu2.3 | USN-6411-1 |
| Ubuntu 20.04 LTS | exim4 | 4.93-13ubuntu1.8 | USN-6411-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 18.04 LTS | exim4 | 4.90.1-1ubuntu1.10+esm1 | USN-6411-1 |
| Ubuntu Pro 16.04 LTS | exim4 | 4.86.2-2ubuntu2.6+esm4 | USN-6411-1 |
| Ubuntu Pro 14.04 LTS | exim4 | 4.82-3ubuntu2.4+esm6 | USN-6411-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP5 | exim | 4.94.2-bp155.5.3.1 | openSUSE-SU-2024:0007-1, openSUSE-SU-2023:0293-1 |
| SUSE Package Hub 15 SP4 | exim | 4.94.2-bp155.5.3.1 | openSUSE-SU-2023:0293-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | exim | 4.96.1-1.1 | openSUSE-SU-2024:13282-1 |
| openSUSE Leap 15.5 | exim | 4.94.2-bp155.5.3.1 | openSUSE-SU-2024:0007-1, openSUSE-SU-2023:0293-1 |
| openSUSE Leap 15.4 | exim | 4.94.2-bp155.5.3.1 | openSUSE-SU-2023:0293-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | exim | 4.96.1-r0 | — |
| Alpine v3.23 | exim | 4.96.1-r0 | — |
| Alpine v3.22 | exim | 4.96.1-r0 | — |
| Alpine v3.21 | exim | 4.96.1-r0 | — |
| Alpine v3.20 | exim | 4.96.1-r0 | — |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | exim | 4.96.1-r0 | — |
| Alpine v3.18 | exim | 4.96.1-r0 | — |
| Alpine v3.17 | exim | 4.96.1-r0 | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | exim | 4.96.1-r0 | — |
Advisories 7
- USN-6411-1 exim4 vulnerabilities Ubuntu Security Notices (USN) · Jun 29, 2026
- WID-SEC-2023-2505 Exim: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 10, 2026
- DSA-5512-1 exim4 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- DLA-3599-1 exim4 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2023:0293-1 Security update for exim SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:13282-1 exim-4.96.1-1.1 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:0007-1 Security update for exim SUSE / openSUSE Security Updates · Feb 4, 2026