Out-of-bounds Write Affecting libx11 package, versions <2:1.6.4-3ubuntu0.4+esm1


Severity

Recommended
medium

Based on Ubuntu security rating.

Threat Intelligence

EPSS
0.11% (47th percentile)

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  • Snyk IDSNYK-UBUNTU1804-LIBX11-5710954
  • published16 Jun 2023
  • disclosed28 Jun 2023

Introduced: 16 Jun 2023

CVE-2023-3138  (opens in a new tab)
CWE-787  (opens in a new tab)

How to fix?

Upgrade Ubuntu:18.04 libx11 to version 2:1.6.4-3ubuntu0.4+esm1 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream libx11 package and not the libx11 package as distributed by Ubuntu. See How to fix? for Ubuntu:18.04 relevant fixed versions and status.

A vulnerability was found in libX11. The security flaw occurs because the functions in src/InitExt.c in libX11 do not check that the values provided for the Request, Event, or Error IDs are within the bounds of the arrays that those functions write to, using those IDs as array indexes. They trust that they were called with values provided by an Xserver adhering to the bounds specified in the X11 protocol, as all X servers provided by X.Org do. As the protocol only specifies a single byte for these values, an out-of-bounds value provided by a malicious server (or a malicious proxy-in-the-middle) can only overwrite other portions of the Display structure and not write outside the bounds of the Display structure itself, possibly causing the client to crash with this memory corruption.

CVSS Scores

version 3.1