Description
Exim libspf2 Integer Underflow Remote Code Execution Vulnerability. This vulnerability allows network-adjacent attackers to execute arbitrary code on affected installations of Exim libspf2. Authentication is not required to exploit this vulnerability.
The specific flaw exists within the parsing of SPF macros. When parsing SPF macros, the process does not properly validate user-supplied data, which can result in an integer underflow before writing to memory. An attacker can leverage this vulnerability to execute code in the context of the service account.
. Was ZDI-CAN-17578.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Exim | libspf2 | exim 4.96-RC0-14-24b8ed847-XX | — |
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 | libspf2 | No fix yet | — |
| Debian 13 | libspf2 | No fix yet | — |
| Debian 12 | libspf2 | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | exim4 +1 | No fix yet | — |
| Ubuntu 26.04 LTS | exim4 +1 | No fix yet | — |
| Ubuntu 25.10 | exim4 +1 | No fix yet | — |
| Ubuntu 24.04 LTS | exim4 +1 | No fix yet | — |
| Ubuntu 22.04 LTS | exim4 +1 | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 20.04 LTS | libspf2 | No fix yet | — |
| Ubuntu Pro 20.04 LTS | exim4 | No fix yet | — |
| Ubuntu Pro 18.04 LTS | exim4 +1 | No fix yet | — |
| Ubuntu Pro 16.04 LTS | exim4 +1 | No fix yet | — |
| Ubuntu Pro 14.04 LTS | exim4 | No fix yet | — |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | libspf2 | 1.2.11-r3 | — |
| Alpine v3.23 | libspf2 | 1.2.11-r3 | — |
| Alpine v3.22 | libspf2 | 1.2.11-r3 | — |
| Alpine v3.21 | libspf2 | 1.2.11-r3 | — |
| Alpine v3.20 | libspf2 | 1.2.11-r3 | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | libspf2 | 1.2.11-r3 | — |
| Alpine v3.18 | libspf2 | 1.2.11-r3 | — |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | exim | 4.96.1-r0 | — |
| Wolfi rolling | libspf2 +2 | No fix yet | — |
Advisories 1
- WID-SEC-2023-2505 Exim: Mehrere Schwachstellen BSI CERT-Bund (WID) · Jun 10, 2026