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Bug 762460 (CVE-2020-27837) - <gnome-base/gdm-40.0: authentication bypass (CVE-2020-27837)
Summary: <gnome-base/gdm-40.0: authentication bypass (CVE-2020-27837)
Status: IN_PROGRESS
Alias: CVE-2020-27837
Product: Gentoo Security
Classification: Unclassified
Component: Vulnerabilities (show other bugs)
Hardware: All Linux
: Normal minor (vote)
Assignee: Gentoo Security
URL: https://gitlab.gnome.org/GNOME/gdm/-/...
Whiteboard: B4 [glsa?]
Keywords:
Depends on:
Blocks:
 
Reported: 2020-12-29 19:57 UTC by John Helmert III
Modified: 2021-08-07 03:25 UTC (History)
0 users

See Also:
Package list:
Runtime testing required: ---


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Description John Helmert III gentoo-dev Security 2020-12-29 19:57:43 UTC
CVE-2020-27837:

A flaw was found in GDM in versions prior to 3.38.2.1. A race condition in the handling of session shutdown makes it possible to bypass the lock screen for a user that has autologin enabled, accessing their session without authentication. This is similar to CVE-2017-12164, but requires more difficult conditions to exploit.


Maintainers, please confirm if we are vulnerable (I suspect the CVE text might
be wrong).
Comment 1 Larry the Git Cow gentoo-dev 2021-04-30 16:08:48 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=b7cbef6cf8bcca85cbb0594e62226c8a6a262b69

commit b7cbef6cf8bcca85cbb0594e62226c8a6a262b69
Author:     Matt Turner <mattst88@gentoo.org>
AuthorDate: 2021-04-30 02:27:41 +0000
Commit:     Matt Turner <mattst88@gentoo.org>
CommitDate: 2021-04-30 16:08:16 +0000

    gnome-base/gdm: Version bump to 40.0
    
    * Drop 49-keychain and 50-ssh-agent files (bugs #549102, #692648)
    * Switch to Meson (resolves bug #585976)
    ** Remove unnecessary fontconfig, libXext, iso-codes, libgudev,
       libXinerama dependencies
    * Remove unused introspection, smartcard, xinerama USE flags
    * Depend on xorg-server[-minimal] (bug #660546)
    * Resolve bug #613222, resolved upstream in v40.0
    * Resolve bug #733708, resolved upstream in v3.38
    
    Bug: https://bugs.gentoo.org/762460
    Closes: https://bugs.gentoo.org/549102
    Closes: https://bugs.gentoo.org/585976
    Closes: https://bugs.gentoo.org/613222
    Closes: https://bugs.gentoo.org/660546
    Closes: https://bugs.gentoo.org/692648
    Closes: https://bugs.gentoo.org/733708
    Signed-off-by: Matt Turner <mattst88@gentoo.org>

 gnome-base/gdm/Manifest                            |   1 +
 ...dm-40.0-meson-allow-building-with-elogind.patch | 211 +++++++++++++++++++++
 gnome-base/gdm/gdm-40.0.ebuild                     | 207 ++++++++++++++++++++
 3 files changed, 419 insertions(+)
Comment 2 John Helmert III gentoo-dev Security 2021-05-12 02:22:27 UTC
Thanks! Please stable when ready.
Comment 3 Larry the Git Cow gentoo-dev 2021-05-31 02:00:05 UTC
The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=4d317fa1ab038e3fcdd86897a869fc4c8d59c247

commit 4d317fa1ab038e3fcdd86897a869fc4c8d59c247
Author:     Matt Turner <mattst88@gentoo.org>
AuthorDate: 2021-05-30 23:32:42 +0000
Commit:     Matt Turner <mattst88@gentoo.org>
CommitDate: 2021-05-31 01:57:51 +0000

    gnome-base/gdm: Drop old versions
    
    Bug: https://bugs.gentoo.org/762460
    Signed-off-by: Matt Turner <mattst88@gentoo.org>

 gnome-base/gdm/Manifest                            |   1 -
 .../gdm/files/gdm-2.32.0-xinitrc-ssh-agent.patch   |  32 ---
 gnome-base/gdm/files/gdm-CanGraphical-wait.patch   | 189 -----------------
 gnome-base/gdm/gdm-3.36.4-r1.ebuild                | 228 ---------------------
 4 files changed, 450 deletions(-)
Comment 4 John Helmert III gentoo-dev Security 2021-05-31 16:57:34 UTC
Thanks!
Comment 5 NATTkA bot gentoo-dev 2021-07-29 17:24:50 UTC Comment hidden (obsolete)
Comment 6 NATTkA bot gentoo-dev 2021-07-29 17:33:22 UTC Comment hidden (obsolete)
Comment 7 NATTkA bot gentoo-dev 2021-07-29 17:41:13 UTC Comment hidden (obsolete)
Comment 8 NATTkA bot gentoo-dev 2021-07-29 17:49:23 UTC Comment hidden (obsolete)
Comment 9 NATTkA bot gentoo-dev 2021-07-29 18:05:18 UTC Comment hidden (obsolete)
Comment 10 NATTkA bot gentoo-dev 2021-07-29 18:13:37 UTC
Package list is empty or all packages have requested keywords.