IRSSI-SA-2017-10 Irssi Security Advisory [1]
============================================
CVE-2017-15228, CVE-2017-15227, CVE-2017-15721, CVE-2017-15723,
CVE-2017-15722

Description
-----------

Multiple vulnerabilities have been located in Irssi.

(a) When installing themes with unterminated colour formatting
    sequences, Irssi may access data beyond the end of the
    string. (CWE-126) Found by Hanno Böck.

    CVE-2017-15228 was assigned to this issue.

(b) While waiting for the channel synchronisation, Irssi may
    incorrectly fail to remove destroyed channels from the query list,
    resulting in use after free conditions when updating the state
    later on. Found by Joseph Bisch. (CWE-416 caused by CWE-672)

    CVE-2017-15227 was assigned to this issue.

(c) Certain incorrectly formatted DCC CTCP messages could cause NULL
    pointer dereference. Found by Joseph Bisch. This is a separate,
    but similar issue to CVE-2017-9468. (CWE-690)

    CVE-2017-15721 was assigned to this issue.

(d) Overlong nicks or targets may result in a NULL pointer dereference
    while splitting the message. Found by Joseph Bisch. (CWE-690)

    CVE-2017-15723 was assigned to this issue.

(e) In certain cases Irssi may fail to verify that a Safe channel ID
    is long enough, causing reads beyond the end of the string. Found
    by Joseph Bisch. (CWE-126)

    CVE-2017-15722 was assigned to this issue.


Impact
------

(a,b,c,d) May result in denial of service (remote crash).

(e) May affect the stability of Irssi.


Affected versions
-----------------

(a,b,c,e) All Irssi versions that we observed.

(d) Starting from 0.8.17.


Fixed in
--------

Irssi 1.0.5


Recommended action
------------------

Upgrade to Irssi 1.0.5. Irssi 1.0.5 is a maintenance release in the
1.0 series, without any new features.

After installing the updated packages, one can issue the /upgrade
command to load the new binary. TLS connections will require
/reconnect.


Mitigating facts
----------------

(a) requires user to install malicious or broken theme file

(b,c,e) requires a broken ircd or control over the ircd

(d) irc servers typically have length limits in place


Patch
-----

https://github.com/irssi/irssi/commit/43e44d553d44e313003cee87e6ea5e24d68b84a1


References
----------

[1] https://irssi.org/security/irssi_sa_2017_10.txt