Use-after-free vulnerability in OpenSMTPD before 5.7.2 allows remote attackers to cause a denial of service (crash) or execute arbitrary code via vectors involving req_ca_vrfy_smtp and req_ca_vrfy_mta.

Issues fixed in this release (since 5.7.2): - fix an mda buffer truncation bug which allows a user to create forward files that pass session checks but fail delivery later down the chain, within the user mda; - fix remote buffer overflow in unprivileged pony process; - reworked offline enqueue to better protect against hardlink attacks.
---- 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:
http://seclists.org/oss-sec/2015/q4/17 MITRE has assigned one CVE for the use-after-free vulnerability; additional CVEs may be assigned:
http://seclists.org/oss-sec/2015/q4/23 External References:
https://www.opensmtpd.org/announces/release-5.7.2.txt http://seclists.org/oss- sec/2015/q4/17

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

OpenSMTPD developers report :

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

ID	Name	Product	Family	Severity
89469	Fedora 22 : opensmtpd-5.7.3p1-1.fc22 (2015-fd133d52cc)	Nessus	Fedora Local Security Checks	critical
89451	Fedora 23 : opensmtpd-5.7.3p1-1.fc23 (2015-ed1c673f09)	Nessus	Fedora Local Security Checks	critical
86268	FreeBSD : OpenSMTPD -- multiple vulnerabilities (ee7bdf7f-11bb-4eea-b054-c692ab848c20)	Nessus	FreeBSD Local Security Checks	critical

Detections

Analytics

CVE-2015-7687

critical

Tenable Plugins

critical

critical

critical