It was discovered that sympa, a modern mailing list manager, would crash when processing certain types of malformed messages.
For the stable distribution (etch), this problem has been fixed in version 5.2.3-1.2+etch1.
For the unstable distribution (sid), this problem has been fixed in version 5.3.4-4.
We recommend that you upgrade your sympa package.
MD5 checksums of the listed files are available in the original advisory.