| Name | CVE-2023-51766 |
| Description | Exim before 4.97.1 allows SMTP smuggling in certain PIPELINING/CHUNKING configurations. Remote attackers can use a published exploitation technique to inject e-mail messages with a spoofed MAIL FROM address, allowing bypass of an SPF protection mechanism. This occurs because Exim supports <LF>.<CR><LF> but some other popular e-mail servers do not. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-3708-1, DSA-5597-1, ELA-1126-1 |
| Debian Bugs | 1059387 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| exim4 (PTS) | jessie, jessie (lts) | 4.84.2-2+deb8u12 | fixed |
| stretch (security) | 4.89-2+deb9u8 | vulnerable | |
| stretch (lts), stretch | 4.89-2+deb9u13 | fixed | |
| buster, buster (lts) | 4.92-8+deb10u10 | fixed | |
| buster (security) | 4.92-8+deb10u9 | fixed | |
| bullseye | 4.94.2-7+deb11u3 | fixed | |
| bullseye (security) | 4.94.2-7+deb11u4 | fixed | |
| bookworm | 4.96-15+deb12u6 | fixed | |
| bookworm (security) | 4.96-15+deb12u5 | fixed | |
| sid, trixie | 4.98-2 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| exim4 | source | jessie | 4.84.2-2+deb8u12 | ELA-1126-1 | ||
| exim4 | source | stretch | 4.89-2+deb9u12 | ELA-1126-1 | ||
| exim4 | source | buster | 4.92-8+deb10u9 | DLA-3708-1 | ||
| exim4 | source | bullseye | 4.94.2-7+deb11u2 | DSA-5597-1 | ||
| exim4 | source | bookworm | 4.96-15+deb12u4 | DSA-5597-1 | ||
| exim4 | source | (unstable) | 4.97-3 | 1059387 |
https://sec-consult.com/blog/detail/smtp-smuggling-spoofing-e-mails-worldwide/
https://www.openwall.com/lists/oss-security/2023/12/21/6
https://bugs.exim.org/show_bug.cgi?id=3063
https://exim.org/static/doc/security/CVE-2023-51766.txt
https://git.exim.org/exim.git/commit/cf1376206284f2a4f11e32d931d4aade34c206c5 (exim-4.98-RC0)
https://git.exim.org/exim.git/commit/4596719398f6f2365bed563aafd757a6433ce7b4 (exim-4.98-RC0)
https://git.exim.org/exim.git/commit/5bb786d5ad568a88d50d15452aacc8404047e5ca (exim-4.98-RC0)