CVE-2023-3138

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.

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.

Core X11 protocol client library.

Security Fix(es):

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.(CVE-2023-3138)

Core X11 protocol client library.

Security Fix(es):

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.(CVE-2023-3138)

Core X11 protocol client library.

Security Fix(es):

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.(CVE-2023-3138)

Core X11 protocol client library.

Security Fix(es):

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.(CVE-2023-3138)

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.

The libX11 packages contain the core X11 protocol client library.

Security Fix(es):

• libX11: InitExt.c can overwrite unintended portions of the Display structure if the extension request leads to a buffer overflow (CVE-2023-3138)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

The libX11 packages contain the core X11 protocol client library.

Security Fix(es):

• libX11: InitExt.c can overwrite unintended portions of the Display structure if the extension request leads to a buffer overflow (CVE-2023-3138)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Additional Changes:

For detailed information on changes in this release, see the AlmaLinux Release Notes linked from the References section.

• CVE-2023-3138: prevent out-of-bounds writes in XQueryExtension responses within Display struct

• CVE-2018-14599: fix off-by-one writes in XListExtensions, XGetFontPath and XListFonts
• CVE-2018-14600: fix out-of-bounds write in XListExtensions and XGetFontPath
• CVE-2018-14598: fix crash on invalid reply in XListExtensions and XGetFontPath
• CVE-2021-31535: reject strings longer than USHRT_MAX before sending them on the wire
• CVE-2023-3138: add bounds checks for extension request, event and error codes
• CVE-2023-43787: fix integer overflow in XCreateImage leading to heap overflow

• CVE-2018-14599: fix off-by-one writes in XListExtensions, XGetFontPath and XListFonts
• CVE-2018-14600: fix out-of-bounds write in XListExtensions and XGetFontPath
• CVE-2018-14598: fix crash on invalid reply in XListExtensions and XGetFontPath
• CVE-2021-31535: reject strings longer than USHRT_MAX before sending them on the wire
• CVE-2023-3138: add bounds checks for extension request, event and error codes
• CVE-2023-43787: fix integer overflow in XCreateImage leading to heap overflow

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.

Buffer overflows in InitExt.c in libX11 prior to 1.8.6. (CVE-2023-3138)

These are all security issues fixed in the libX11-6-1.8.5-2.1 package on the GA media of openSUSE Tumbleweed.

This update for libX11 fixes the following issues:

• CVE-2023-3138: Fixed buffer overflows in InitExt.c (bsc#1212102).

This update for libX11 fixes the following issues:

• CVE-2023-3138: Fixed buffer overflows in InitExt.c (bsc#1212102).

Gregory James Duck discovered that libx11 incorrectly handled certain Request, Event, or Error IDs. If a user were tricked into connecting to a malicious X Server, a remote attacker could possibly use this issue to cause libx11 to crash, resulting in a denial of service.

USN-6168-1 fixed a vulnerability in libx11. This update provides the corresponding update for Ubuntu 14.04 ESM, Ubuntu 16.04 ESM, and Ubuntu 18.04 ESM.

Original advisory details:

Gregory James Duck discovered that libx11 incorrectly handled certain Request, Event, or Error IDs. If a user were tricked into connecting to a malicious X Server, a remote attacker could possibly use this issue to cause libx11 to crash, resulting in a denial of service.