Description
The receive_msg function in receive.c in the SMTP daemon in Exim 4.88 and 4.89 allows remote attackers to cause a denial of service (infinite loop and stack exhaustion) via vectors involving BDAT commands and an improper check for a '.' character signifying the end of the content, related to the bdat_getc function.
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 | 4.89-13 | — |
| Debian 13 | exim4 | 4.89-13 | — |
| Debian 12 | exim4 | 4.89-13 | — |
| Debian 9 | exim4 | 4.89-2+deb9u2 | DSA-4053-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SUSE Package Hub 15 SP2 | exim | 4.94.2-bp152.6.4.1 | openSUSE-SU-2021:0754-1 |
| SUSE Package Hub 15 SP2 | libspf2 | 1.2.10-bp152.5.1 | openSUSE-SU-2021:0754-1 |
| SUSE Package Hub 15 SP1 | exim | 4.94.2-bp151.2.4.1 | openSUSE-SU-2021:0753-1 |
| SUSE Package Hub 15 SP1 | libspf2 | 1.2.10-bp151.4.1 | openSUSE-SU-2021:0753-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | exim | 4.94.2-4.2 | openSUSE-SU-2024:10746-1 |
| openSUSE Leap 15.2 | exim | 4.94.2-lp152.8.3.1 | openSUSE-SU-2021:0677-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | exim | 4.89.1-r0 | — |
| Alpine v3.23 | exim | 4.89.1-r0 | — |
| Alpine v3.22 | exim | 4.89.1-r0 | — |
| Alpine v3.21 | exim | 4.89.1-r0 | — |
| Alpine v3.20 | exim | 4.89.1-r0 | — |
Show 13 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.19 | exim | 4.89.1-r0 | — |
| Alpine v3.18 | exim | 4.89.1-r0 | — |
| Alpine v3.17 | exim | 4.89.1-r0 | — |
| Alpine v3.16 | exim | 4.89.1-r0 | — |
| Alpine v3.15 | exim | 4.89.1-r0 | — |
| Alpine v3.14 | exim | 4.89.1-r0 | — |
| Alpine v3.13 | exim | 4.89.1-r0 | — |
| Alpine v3.12 | exim | 4.89.1-r0 | — |
| Alpine v3.11 | exim | 4.89.1-r0 | — |
| Alpine v3.10 | exim | 4.89.1-r0 | — |
| Alpine v3.9 | exim | 4.89.1-r0 | — |
| Alpine v3.8 | exim | 4.89.1-r0 | — |
| Alpine v3.7 | exim | 4.89.1-r0 | — |
Public exploits
Exploit or proof-of-concept code for this vulnerability is publicly available, which lowers the bar for attackers. Treat it as a reason to patch sooner.
Exploit-DB 1
- Exim 4.89 - 'BDAT' Denial of Service EDB-43184 · dos · Nov 27, 2017 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 5
- DSA-4053-1 exim4 - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2021:0754-1 Security update for exim SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2024:10746-1 exim-4.94.2-4.2 on GA media SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0677-1 Security update for exim SUSE / openSUSE Security Updates · Feb 4, 2026
- openSUSE-SU-2021:0753-1 Security update for exim SUSE / openSUSE Security Updates · Feb 4, 2026
References
- https://lists.exim.org/lurker/message/20171125.034842.d1d75cac.en.html
- http://openwall.com/lists/oss-security/2017/11/25/3
- https://bugs.exim.org/show_bug.cgi?id=2201
- http://openwall.com/lists/oss-security/2017/11/25/1
- 1039873 vdb-entry
- http://openwall.com/lists/oss-security/2017/11/25/2
- DSA-4053 vendor-advisory
- 43184 exploit
- [oss-security] 20210504 21Nails: Multiple vulnerabilities in Exim mailing-list