Several vulnerabilities have been fixed in OpenSMTPD 5.7.2:
- an oversight in the portable version of fgetln() that allows attackers to read and write out-of-bounds memory;
- multiple denial-of-service vulnerabilities that allow local users to kill or hang OpenSMTPD;
- a stack-based buffer overflow that allows local users to crash OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;
- a hardlink attack (or race-conditioned symlink attack) that allows local users to unset the chflags() of arbitrary files;
- a hardlink attack that allows local users to read the first line of arbitrary files (for example, root's hash from /etc/master.passwd);
- a denial-of-service vulnerability that allows remote attackers to fill OpenSMTPD's queue or mailbox hard-disk partition;
- an out-of-bounds memory read that allows remote attackers to crash OpenSMTPD, or leak information and defeat the ASLR protection;
- a use-after-free vulnerability that allows remote attackers to crash OpenSMTPD, or execute arbitrary code as the non-chrooted _smtpd user;
Further details can be found in Qualys' audit report:
MITRE has assigned one CVE for the use-after-free vulnerability; additional CVEs may be assigned:
Created opensmtpd tracking bugs for this issue:
Affects: fedora-all [bug 1268794]
Affects: epel-all [bug 1268795]
This update is already in testing. Just edited the descriptions on Bodhi to be more specific on vulnerabilities fixed, and added bugs above.
Everybody interested is encouraged to test the update and give feedback.
Fixed in opensmtpd version 5.7.3 which is on stable.