GNOME Shell 3.14.x before 3.14.1, when the Screen Lock feature is used, does not limit the aggregate memory consumption of all active PrtSc requests, which allows physically proximate attackers to execute arbitrary commands on an unattended workstation by making many PrtSc requests and leveraging a temporary lock outage, and the resulting temporary shell availability, caused by the Linux kernel OOM killer.

gnome-settings-daemon was updated to fix a bug and a security issue :

Security issue fixed :

  - CVE-2014-7300: The lockscreen can be bypassed with the     Print Screen button.

Bug fixed :

  - Do not hide the cursor while there was no mutter running     (bsc#905158).

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

It was found that the GNOME shell did not disable the Print Screen key when the screen was locked. This could allow an attacker with physical access to a system with a locked screen to crash the screen-locking application by creating a large amount of screenshots. (CVE-2014-7300)

This update also fixes the following bugs :

  - The Timed Login feature, which automatically logs in a     specified user after a specified period of time, stopped     working after the first user of the GUI logged out. This     has been fixed, and the specified user is always logged     in if no one else logs in.

  - If two monitors were arranged vertically with the     secondary monitor above the primary monitor, it was     impossible to move windows onto the secondary monitor.
    With this update, windows can be moved through the upper     edge of the first monitor to the secondary monitor.

  - If the Gnome Display Manager (GDM) user list was     disabled and a user entered the user name, the password     prompt did not appear. Instead, the user had to enter     the user name one more time. The GDM code that contained     this error has been fixed, and users can enter their     user names and passwords as expected.

  - Prior to this update, only a small area was available on     the GDM login screen for a custom text banner. As a     consequence, when a long banner was used, it did not fit     into the area, and the person reading the banner had to     use scrollbars to view the whole text. With this update,     more space is used for the banner if necessary, which     allows the user to read the message conveniently.

  - When the Cancel button was pressed while an LDAP user     name and password was being validated, the GDM code did     not handle the situation correctly. As a consequence,     GDM became unresponsive, and it was impossible to return     to the login screen. The affected code has been fixed,     and LDAP user validation can be canceled, allowing     another user to log in instead.

  - If the window focus mode in GNOME was set to 'mouse' or     'sloppy', navigating through areas of a pop-up menu     displayed outside its parent window caused the window to     lose its focus. Consequently, the menu was not usable.
    This has been fixed, and the window focus is kept in     under this scenario.

  - If user authentication is configured to require a smart     card to log in, user names are obtained from the smart     card. The authentication is then performed by entering     the smart card PIN. Prior to this update, the login     screen allowed a user name to be entered if no smart     card was inserted, but due to a bug in the underlying     code, the screen became unresponsive. If, on the other     hand, a smart card was used for authentication, the user     was logged in as soon as the authentication was     complete. As a consequence, it was impossible to select     a session other than GNOME Classic. Both of these     problems have been fixed. Now, a smart card is required     when this type of authentication is enabled, and any     other installed session can be selected by the user.

In addition, this update adds the following enhancement :

  - Support for quad-buffer OpenGL stereo visuals has been     added. As a result, OpenGL applications that use     quad-buffer stereo can be run and properly displayed     within the GNOME desktop when used with a video driver     and hardware with the necessary capabilities.

Updated gnome-shell, mutter, clutter, and cogl packages that fix one security issue, several bugs, and add one enhancement are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

GNOME Shell and the packages it depends upon provide the core user interface of the Red Hat Enterprise Linux desktop, including functions such as navigating between windows and launching applications.

It was found that the GNOME shell did not disable the Print Screen key when the screen was locked. This could allow an attacker with physical access to a system with a locked screen to crash the screen-locking application by creating a large amount of screenshots. (CVE-2014-7300)

This update also fixes the following bugs :

* The Timed Login feature, which automatically logs in a specified user after a specified period of time, stopped working after the first user of the GUI logged out. This has been fixed, and the specified user is always logged in if no one else logs in. (BZ#1043571)

* If two monitors were arranged vertically with the secondary monitor above the primary monitor, it was impossible to move windows onto the secondary monitor. With this update, windows can be moved through the upper edge of the first monitor to the secondary monitor. (BZ#1075240)

* If the Gnome Display Manager (GDM) user list was disabled and a user entered the user name, the password prompt did not appear. Instead, the user had to enter the user name one more time. The GDM code that contained this error has been fixed, and users can enter their user names and passwords as expected. (BZ#1109530)

* Prior to this update, only a small area was available on the GDM login screen for a custom text banner. As a consequence, when a long banner was used, it did not fit into the area, and the person reading the banner had to use scrollbars to view the whole text. With this update, more space is used for the banner if necessary, which allows the user to read the message conveniently. (BZ# 1110036)

* When the Cancel button was pressed while an LDAP user name and password was being validated, the GDM code did not handle the situation correctly. As a consequence, GDM became unresponsive, and it was impossible to return to the login screen. The affected code has been fixed, and LDAP user validation can be canceled, allowing another user to log in instead. (BZ#1137041)

* If the window focus mode in GNOME was set to 'mouse' or 'sloppy', navigating through areas of a pop-up menu displayed outside its parent window caused the window to lose its focus. Consequently, the menu was not usable. This has been fixed, and the window focus is kept in under this scenario. (BZ#1149585)

* If user authentication is configured to require a smart card to log in, user names are obtained from the smart card. The authentication is then performed by entering the smart card PIN. Prior to this update, the login screen allowed a user name to be entered if no smart card was inserted, but due to a bug in the underlying code, the screen became unresponsive. If, on the other hand, a smart card was used for authentication, the user was logged in as soon as the authentication was complete. As a consequence, it was impossible to select a session other than GNOME Classic. Both of these problems have been fixed. Now, a smart card is required when this type of authentication is enabled, and any other installed session can be selected by the user.
(BZ#1159385, BZ# 1163474)

In addition, this update adds the following enhancement :

* Support for quad-buffer OpenGL stereo visuals has been added. As a result, OpenGL applications that use quad-buffer stereo can be run and properly displayed within the GNOME desktop when used with a video driver and hardware with the necessary capabilities. (BZ#861507, BZ#1108890, BZ#1108891, BZ# 1108893)

All GNOME Shell users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement.

From Red Hat Security Advisory 2015:0535 :

Updated gnome-shell, mutter, clutter, and cogl packages that fix one security issue, several bugs, and add one enhancement are now available for Red Hat Enterprise Linux 7.

Red Hat Product Security has rated this update as having Low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link in the References section.

GNOME Shell and the packages it depends upon provide the core user interface of the Red Hat Enterprise Linux desktop, including functions such as navigating between windows and launching applications.

It was found that the GNOME shell did not disable the Print Screen key when the screen was locked. This could allow an attacker with physical access to a system with a locked screen to crash the screen-locking application by creating a large amount of screenshots. (CVE-2014-7300)

This update also fixes the following bugs :

* The Timed Login feature, which automatically logs in a specified user after a specified period of time, stopped working after the first user of the GUI logged out. This has been fixed, and the specified user is always logged in if no one else logs in. (BZ#1043571)

* If two monitors were arranged vertically with the secondary monitor above the primary monitor, it was impossible to move windows onto the secondary monitor. With this update, windows can be moved through the upper edge of the first monitor to the secondary monitor. (BZ#1075240)

* If the Gnome Display Manager (GDM) user list was disabled and a user entered the user name, the password prompt did not appear. Instead, the user had to enter the user name one more time. The GDM code that contained this error has been fixed, and users can enter their user names and passwords as expected. (BZ#1109530)

* Prior to this update, only a small area was available on the GDM login screen for a custom text banner. As a consequence, when a long banner was used, it did not fit into the area, and the person reading the banner had to use scrollbars to view the whole text. With this update, more space is used for the banner if necessary, which allows the user to read the message conveniently. (BZ# 1110036)

* When the Cancel button was pressed while an LDAP user name and password was being validated, the GDM code did not handle the situation correctly. As a consequence, GDM became unresponsive, and it was impossible to return to the login screen. The affected code has been fixed, and LDAP user validation can be canceled, allowing another user to log in instead. (BZ#1137041)

* If the window focus mode in GNOME was set to 'mouse' or 'sloppy', navigating through areas of a pop-up menu displayed outside its parent window caused the window to lose its focus. Consequently, the menu was not usable. This has been fixed, and the window focus is kept in under this scenario. (BZ#1149585)

* If user authentication is configured to require a smart card to log in, user names are obtained from the smart card. The authentication is then performed by entering the smart card PIN. Prior to this update, the login screen allowed a user name to be entered if no smart card was inserted, but due to a bug in the underlying code, the screen became unresponsive. If, on the other hand, a smart card was used for authentication, the user was logged in as soon as the authentication was complete. As a consequence, it was impossible to select a session other than GNOME Classic. Both of these problems have been fixed. Now, a smart card is required when this type of authentication is enabled, and any other installed session can be selected by the user.
(BZ#1159385, BZ# 1163474)

In addition, this update adds the following enhancement :

* Support for quad-buffer OpenGL stereo visuals has been added. As a result, OpenGL applications that use quad-buffer stereo can be run and properly displayed within the GNOME desktop when used with a video driver and hardware with the necessary capabilities. (BZ#861507, BZ#1108890, BZ#1108891, BZ# 1108893)

All GNOME Shell users are advised to upgrade to these updated packages, which contain backported patches to correct these issues and add this enhancement.

- Add gnome-settings-daemon-no-lockscreen-screenshot.patch :

  + media-keys: Disallow screenshots when locked     (boo#900031, bgo#737456, CVE-2014-7300).

Security fix for lock screen circumvention by consecutive screenshot requests triggering OOM situation

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.

ID	Name	Product	Family	Severity
83700	SUSE SLED12 / SLES12 Security Update : gnome-settings-daemon (SUSE-SU-2015:0515-1)	Nessus	SuSE Local Security Checks	high
82249	Scientific Linux Security Update : GNOME Shell on SL7.x x86_64 (20150305)	Nessus	Scientific Linux Local Security Checks	high
81898	CentOS 7 : clutter / cogl / gnome-shell / mutter (CESA-2015:0535)	Nessus	CentOS Local Security Checks	high
81807	Oracle Linux 7 : GNOME / Shell (ELSA-2015-0535)	Nessus	Oracle Linux Local Security Checks	high
81639	RHEL 7 : GNOME Shell (RHSA-2015:0535)	Nessus	Red Hat Local Security Checks	high
78836	openSUSE Security Update : gnome-settings-daemon (openSUSE-SU-2014:1348-1)	Nessus	SuSE Local Security Checks	high
78569	Fedora 20 : gnome-shell-3.10.4-9.fc20 (2014-12690)	Nessus	Fedora Local Security Checks	high

Detections

Analytics

CVE-2014-7300

medium

Tenable Plugins

high

high

high

high

high

high

high