The official znc docker images before 1.7.1-slim contain a blank password for a root user. Systems using the znc docker container deployed by affected versions of the Docker image may allow an remote attacker to achieve root access with a blank password.

Last updated 25 August 2025

NULL pointer dereference vulnerability in ZNC before 0.092 caused by traffic stats when there are unauthenticated connections.

Directory traversal vulnerability in ZNC before 0.072 allows remote attackers to overwrite arbitrary files via a crafted DCC SEND request.

An out-of-range flaw was found in znc where if it received a "PING" from a client without an argument, std::string would throw a std::outofrange exception which killed znc. This is fixed in subversion [1].

Some unsafe substr() calls were fixed as well. These are of lesser impact because a valid login is required in order to cause a std::outofrange exception. This is also fixed in subversion [2].

[1] http://znc.svn.sourceforge.net/viewvc/znc?view=revision&revision=2093 [2] http://znc.svn.sourceforge.net/viewvc/znc?view=revision&revision=2095

Multiple CRLF injection vulnerabilities in webadmin in ZNC before 0.066 allow remote authenticated users to modify the znc.conf configuration file and gain privileges via CRLF sequences in the quit message and other vectors.

ZNC before 1.7.1-rc1 does not properly validate untrusted lines coming from the network, allowing a non-admin user to escalate his privilege and inject rogue values into znc.conf.

Last updated 26 August 2025

ZNC 1.8.0 up to 1.8.1-rc1 allows authenticated users to trigger an application crash (with a NULL pointer dereference) if echo-message is not enabled and there is no network.

ZNC before 1.7.1-rc1 is prone to a path traversal flaw via ../ in a web skin name to access files outside of the intended skins directories.

The CBounceDCCMod::OnPrivCTCP function in bouncedcc.cpp in the bouncedcc module in ZNC 0.200 and 0.202 allows remote attackers to cause a denial of service (crash) via a crafted DCC RESUME request.

Multiple unspecified vulnerabilities in ZNC 0.092 allow remote attackers to cause a denial of service (exception and daemon crash) via unknown vectors related to "unsafe substr() calls."

An out-of-range flaw was found in znc where if it received a "PING" from a client without an argument, std::string would throw a std::outofrange exception which killed znc. This is fixed in subversion [1].

Some unsafe substr() calls were fixed as well. These are of lesser impact because a valid login is required in order to cause a std::outofrange exception. This is also fixed in subversion [2].

[1] http://znc.svn.sourceforge.net/viewvc/znc?view=revision&revision=2093 [2] http://znc.svn.sourceforge.net/viewvc/znc?view=revision&revision=2095

Stack-based buffer overflow in fish.cpp in the Fish plugin for ZNC, as used in ZNC for Windows (znc-msvc) 0.206 and earlier, allows remote attackers to cause a denial of service (crash) via a long string in a DH1080INIT message.

ZNC 1.0 allows remote authenticated users to cause a denial of service (NULL pointer reference and crash) via a crafted request to the (1) editnetwork, (2) editchan, (3) addchan, or (4) delchan page in modules/webadmin.cpp.

The CWebAdminMod::ChanPage function in modules/webadmin.cpp in ZNC before 1.4 allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) by adding a channel with the same name as an existing channel but without the leading # character, related to a "use-after-delete" error.

znc.cpp in ZNC before 0.092 allows remote authenticated users to cause a denial of service (crash) by requesting traffic statistics when there is an active unauthenticated connection, which triggers a NULL pointer dereference, as demonstrated using (1) a traffic link in the web administration pages or (2) the traffic command in the /znc shell.

Hi, https://wiki.znc.in/ChangeLog/1.9.1 https://github.com/znc/znc/commit/8cbf8d628174ddf23da680f3f117dc54da0eb06e ---

Martin