Description
Heap-based buffer overflow in the string_vformat function in string.c in Exim before 4.70 allows remote attackers to execute arbitrary code via an SMTP session that includes two MAIL commands in conjunction with a large message containing crafted headers, leading to improper rejection logging.
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 | 4.70-1 | — |
| Debian 13 | exim4 | 4.70-1 | — |
| Debian 12 | exim4 | 4.70-1 | — |
| Debian 5.0 | exim4 | 4.69-9+lenny1 | DSA-2131-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5 | exim +2 | 4.63-5.el5_5.2 | RHSA-2010:0970 |
| RHEL 4 | exim +3 | 4.43-1.RHEL4.5.el4_8.1 | RHSA-2010:0970 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 5.4 EUS | exim +2 | 4.63-3.el5_4.1 | RHSA-2010:0970 |
| RHEL 5.3 EUS | exim +2 | 4.63-3.el5_3.1 | RHSA-2010:0970 |
| RHEL 4.7 EUS | exim +3 | 4.43-1.RHEL4.5.el4_7.1 | RHSA-2010:0970 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | exim | 4.86.2-2.2 | openSUSE-SU-2024:10017-1 |
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.
Metasploit 1 module
-
Exim4 string_format Function Heap Buffer Overflow
exploit/unix/smtp/exim4_string_format
Exploit-DB 2
- Exim4 < 4.69 - string_format Function Heap Buffer Overflow (Metasploit) EDB-16925 · remote · Dec 16, 2010 · verified
- Exim 4.63 - Remote Command Execution EDB-15725 · remote · Dec 11, 2010 · verified
Sources: PoC-in-GitHub, Metasploit Framework, Exploit-DB — updated daily. Only links are listed; no exploit code is hosted here.
Advisories 3
- RHSA-2010:0970 Red Hat Security Advisory: exim security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-2131-1 exim4 - remote code execution Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2024:10017-1 exim-4.86.2-2.2 on GA media SUSE / openSUSE Security Updates · May 7, 2025
References
- SUSE-SA:2010:059 vendor-advisory
- [exim-dev] 20101207 Remote root vulnerability in Exim mailing-list
- http://bugs.exim.org/show_bug.cgi?id=787
- 1024858 vdb-entry
- RHSA-2010:0970 vendor-advisory
- ADV-2010-3186 vdb-entry
- 45308 vdb-entry
- http://www.metasploit.com/modules/exploit/unix/smtp/exim4_string_format
- http://atmail.com/blog/2010/atmail-6204-now-available/
- 42576 third-party-advisory
- 42587 third-party-advisory
- https://bugzilla.redhat.com/show_bug.cgi?id=661756
- [exim-dev] 20101210 Re: Remote root vulnerability in Exim mailing-list
- 40019 third-party-advisory
- ADV-2010-3172 vdb-entry
- VU#682457 third-party-advisory
- ADV-2010-3181 vdb-entry
- 42586 third-party-advisory
- ADV-2010-3317 vdb-entry
- USN-1032-1 vendor-advisory
- http://www.cpanel.net/2010/12/exim-remote-memory-corruption-vulnerability-notification-cve-2010-4344.html
- 69685 vdb-entry
- 20101213 Exim security issue in historical release mailing-list
- http://www.theregister.co.uk/2010/12/11/exim_code_execution_peril/
- ADV-2010-3246 vdb-entry
- ADV-2010-3204 vdb-entry
- http://git.exim.org/exim.git/commit/24c929a27415c7cfc7126c47e4cad39acf3efa6b
- DSA-2131 vendor-advisory
- ADV-2010-3171 vdb-entry
- 42589 third-party-advisory
- [oss-security] 20101210 Exim remote root mailing-list
- [oss-security] 20210504 21Nails: Multiple vulnerabilities in Exim mailing-list