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CVE Vulnerabilities

CVE-2023-6377

Out-of-bounds Read

Published: Dec 13, 2023 | Modified: Aug 18, 2025
CVSS 3.x
7.8
HIGH
Source:
NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS 2.x
RedHat/V2
RedHat/V3
7.8 IMPORTANT
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Ubuntu
MEDIUM
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Additional information
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2023-6377
CWEhttps://cwe.mitre.org/data/definitions/125.html

A flaw was found in xorg-server. Querying or changing XKB button actions such as moving from a touchpad to a mouse can result in out-of-bounds memory reads and writes. This may allow local privilege escalation or possible remote code execution in cases where X11 forwarding is involved.

Weakness

The product reads data past the end, or before the beginning, of the intended buffer.

Affected Software

NameVendorStart VersionEnd Version
Enterprise_linux_eusRedhat9.2 (including)9.2 (including)
Red Hat Enterprise Linux 6 Extended Lifecycle Support - EXTENSIONRedHattigervnc-0:1.1.0-25.el6_10.14*
Red Hat Enterprise Linux 7RedHattigervnc-0:1.8.0-28.el7_9*
Red Hat Enterprise Linux 7RedHatxorg-x11-server-0:1.20.4-25.el7_9*
Red Hat Enterprise Linux 8RedHattigervnc-0:1.13.1-2.el8_9.4*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-0:1.20.11-22.el8*
Red Hat Enterprise Linux 8RedHatxorg-x11-server-Xwayland-0:21.1.3-15.el8*
Red Hat Enterprise Linux 8.2 Advanced Update SupportRedHattigervnc-0:1.9.0-15.el8_2.6*
Red Hat Enterprise Linux 8.2 Telecommunications Update ServiceRedHattigervnc-0:1.9.0-15.el8_2.6*
Red Hat Enterprise Linux 8.2 Update Services for SAP SolutionsRedHattigervnc-0:1.9.0-15.el8_2.6*
Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update SupportRedHattigervnc-0:1.11.0-8.el8_4.5*
Red Hat Enterprise Linux 8.4 Telecommunications Update ServiceRedHattigervnc-0:1.11.0-8.el8_4.5*
Red Hat Enterprise Linux 8.4 Update Services for SAP SolutionsRedHattigervnc-0:1.11.0-8.el8_4.5*
Red Hat Enterprise Linux 8.6 Extended Update SupportRedHattigervnc-0:1.12.0-6.el8_6.6*
Red Hat Enterprise Linux 8.8 Extended Update SupportRedHattigervnc-0:1.12.0-15.el8_8.4*
Red Hat Enterprise Linux 9RedHattigervnc-0:1.13.1-3.el9_3.3*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-0:1.20.11-24.el9*
Red Hat Enterprise Linux 9RedHatxorg-x11-server-Xwayland-0:22.1.9-5.el9*
Red Hat Enterprise Linux 9.0 Extended Update SupportRedHattigervnc-0:1.11.0-22.el9_0.5*
Red Hat Enterprise Linux 9.2 Extended Update SupportRedHattigervnc-0:1.12.0-14.el9_2.2*
XorgUbuntubionic*
XorgUbuntutrusty*
XorgUbuntuxenial*
Xorg-serverUbuntubionic*
Xorg-serverUbuntudevel*
Xorg-serverUbuntuesm-infra/bionic*
Xorg-serverUbuntuesm-infra/focal*
Xorg-serverUbuntuesm-infra/xenial*
Xorg-serverUbuntufocal*
Xorg-serverUbuntujammy*
Xorg-serverUbuntulunar*
Xorg-serverUbuntumantic*
Xorg-serverUbuntunoble*
Xorg-serverUbuntuoracular*
Xorg-serverUbuntuplucky*
Xorg-serverUbuntuquesting*
Xorg-serverUbuntutrusty*
Xorg-serverUbuntutrusty/esm*
Xorg-serverUbuntuupstream*
Xorg-serverUbuntuxenial*
Xorg-server-hwe-16.04Ubuntuxenial*
Xorg-server-hwe-18.04Ubuntubionic*
Xorg-server-lts-utopicUbuntutrusty*
Xorg-server-lts-vividUbuntutrusty*
Xorg-server-lts-wilyUbuntutrusty*
Xorg-server-lts-xenialUbuntutrusty*
XwaylandUbuntujammy*
XwaylandUbuntulunar*
XwaylandUbuntumantic*
XwaylandUbuntuupstream*

Potential Mitigations

  • Assume all input is malicious. Use an “accept known good” input validation strategy, i.e., use a list of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.
  • When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, “boat” may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as “red” or “blue.”
  • Do not rely exclusively on looking for malicious or malformed inputs. This is likely to miss at least one undesirable input, especially if the code’s environment changes. This can give attackers enough room to bypass the intended validation. However, denylists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.
  • To reduce the likelihood of introducing an out-of-bounds read, ensure that you validate and ensure correct calculations for any length argument, buffer size calculation, or offset. Be especially careful of relying on a sentinel (i.e. special character such as NUL) in untrusted inputs.

References

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