Bug 1927062 (CVE-2021-26937) - CVE-2021-26937 screen: crash when processing combining chars
Summary: CVE-2021-26937 screen: crash when processing combining chars
Alias: CVE-2021-26937
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
Target Milestone: ---
Assignee: Red Hat Product Security
QA Contact:
: 1926949 (view as bug list)
Depends On: 1927063 1927064 1927065 1927066 2048282
Blocks: 1927067
TreeView+ depends on / blocked
Reported: 2021-02-10 00:33 UTC by Doran Moppert
Modified: 2024-06-14 00:13 UTC (History)
10 users (show)

Fixed In Version:
Doc Type: If docs needed, set a value
Doc Text:
A flaw was found in screen. A specially crafted sequence of combining characters could cause an out of bounds write leading to arbitrary code execution. The highest threat from this vulnerability is to data confidentiality and integrity as well as system availability.
Clone Of:
Last Closed: 2021-03-08 13:01:52 UTC

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2021:0742 0 None None None 2021-03-08 10:30:07 UTC
Red Hat Product Errata RHSA-2022:1074 0 None None None 2022-03-28 10:30:58 UTC

Description Doran Moppert 2021-02-10 00:33:43 UTC
A crash was reported in gnu screen when processing a specially crafted sequence of combining characters.  The cause is an out of bounds write, which may be exploitable to cause arbitrary code execution.


Upstream bug:


Comment 1 Doran Moppert 2021-02-10 00:37:44 UTC
Created gnome-screensaver tracking bugs for this issue:

Affects: fedora-all [bug 1927066]

Comment 3 Pedro Sampaio 2021-02-10 12:23:58 UTC
*** Bug 1926949 has been marked as a duplicate of this bug. ***

Comment 4 Doran Moppert 2021-02-11 01:18:16 UTC

This flaw is in utf8 processing; if your screen configuration does not enable utf8 (through configuration such as "defencoding utf-8" in .screenrc), you are not vulnerable.

Comment 9 errata-xmlrpc 2021-03-08 10:30:06 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7

Via RHSA-2021:0742 https://access.redhat.com/errata/RHSA-2021:0742

Comment 10 Product Security DevOps Team 2021-03-08 13:01:52 UTC
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s):


Comment 12 errata-xmlrpc 2022-03-28 10:30:55 UTC
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7.7 Advanced Update Support
  Red Hat Enterprise Linux 7.7 Update Services for SAP Solutions
  Red Hat Enterprise Linux 7.7 Telco Extended Update Support

Via RHSA-2022:1074 https://access.redhat.com/errata/RHSA-2022:1074

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