Canonical Ubuntu Linux 20.04 Lts

Integer overflows were discovered in the functions grub_cmd_initrd and grub_initrd_init in the efilinux component of GRUB2, as shipped in Debian, Red Hat, and Ubuntu (the functionality is not included in GRUB2 upstream), leading to a heap-based buffer overflow. These could be triggered by an extremely large number of arguments to the initrd command on 32-bit architectures, or a crafted filesystem with very large files on any architecture. An attacker could use this to execute arbitrary code and bypass UEFI Secure Boot restrictions. This issue affects GRUB2 version 2.04 and prior versions.

GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.

GRUB2 fails to validate kernel signature when booted directly without shim, allowing secure boot to be bypassed. This only affects systems where the kernel signing certificate has been imported directly into the secure boot database and the GRUB image is booted directly without the use of shim. This issue affects GRUB2 version 2.04 and prior versions.

It was discovered that snapctl user-open allowed altering the $XDG_DATA_DIRS environment variable when calling the system xdg-open. OpenURL() in usersession/userd/launcher.go would alter $XDG_DATA_DIRS to append a path to a directory controlled by the calling snap. A malicious snap could exploit this to bypass intended access restrictions to control how the host system xdg-open script opens the URL and, for example, execute a script shipped with the snap without confinement. This issue did not affect Ubuntu Core systems. Fixed in snapd versions 2.45.1ubuntu0.2, 2.45.1+18.04.2 and 2.45.1+20.04.2.

cloud-init as managed by snapd on Ubuntu Core 16 and Ubuntu Core 18 devices was run without restrictions on every boot, which a physical attacker could exploit by crafting cloud-init user-data/meta-data via external media to perform arbitrary changes on the device to bypass intended security mechanisms such as full disk encryption. This issue did not affect traditional Ubuntu systems. Fixed in snapd version 2.45.2, revision 8539 and core version 2.45.2, revision 9659.

A use-after-free flaw was found in all samba LDAP server versions before 4.10.17, before 4.11.11, before 4.12.4 used in a AC DC configuration. A Samba LDAP user could use this flaw to crash samba.

NVIDIA Virtual GPU Manager and the guest drivers contain a vulnerability in vGPU plugin, in which there is the potential to execute privileged operations, which may lead to denial of service. This affects vGPU version 8.x (prior to 8.4), version 9.x (prior to 9.4) and version 10.x (prior to 10.3).

It was discovered that websockets.c in LibVNCServer prior to 0.9.12 did not properly decode certain WebSocket frames. A malicious attacker could exploit this by sending specially crafted WebSocket frames to a server, causing a heap-based buffer overflow.

Incomplete cleanup from specific special register read operations in some Intel(R) Processors may allow an authenticated user to potentially enable information disclosure via local access.

GnuTLS 3.6.x before 3.6.14 uses incorrect cryptography for encrypting a session ticket (a loss of confidentiality in TLS 1.2, and an authentication bypass in TLS 1.3). The earliest affected version is 3.6.4 (2018-09-24) because of an error in a 2018-09-18 commit. Until the first key rotation, the TLS server always uses wrong data in place of an encryption key derived from an application.

An issue was discovered in Django 2.2 before 2.2.13 and 3.0 before 3.0.7. In cases where a memcached backend does not perform key validation, passing malformed cache keys could result in a key collision, and potential data leakage.

A buffer overflow could occur when parsing and validating SCTP chunks in WebRTC. This could have led to memory corruption and a potentially exploitable crash. This vulnerability affects Firefox ESR < 68.8, Firefox < 76, and Thunderbird < 68.8.0.

A vulnerability was found in DPDK versions 18.11 and above. The vhost-crypto library code is missing validations for user-supplied values, potentially allowing an information leak through an out-of-bounds memory read.

A memory corruption issue was found in DPDK versions 17.05 and above. This flaw is caused by an integer truncation on the index of a payload. Under certain circumstances, the index (a UInt) is copied and truncated into a uint16, which can lead to out of bound indexing and possible memory corruption.

A vulnerability was found in DPDK versions 18.05 and above. A missing check for an integer overflow in vhost_user_set_log_base() could result in a smaller memory map than requested, possibly allowing memory corruption.

An Ubuntu-specific modification to Pulseaudio to provide security mediation for Snap-packaged applications was found to have a bypass of intended access restriction for snaps which plugs any of pulseaudio, audio-playback or audio-record via unloading the pulseaudio snap policy module. This issue affects: pulseaudio 1:8.0 versions prior to 1:8.0-0ubuntu3.12; 1:11.1 versions prior to 1:11.1-1ubuntu7.7; 1:13.0 versions prior to 1:13.0-1ubuntu1.2; 1:13.99.1 versions prior to 1:13.99.1-1ubuntu3.2;

libfreerdp/core/update.c in FreeRDP versions > 1.1 through 2.0.0-rc4 has an Out-of-bounds Read.

libfreerdp/cache/bitmap.c in FreeRDP versions > 1.0 through 2.0.0-rc4 has an Out of bounds read.

libfreerdp/codec/interleaved.c in FreeRDP versions > 1.0 through 2.0.0-rc4 has an Out-of-bounds Write.

libfreerdp/gdi/region.c in FreeRDP versions > 1.0 through 2.0.0-rc4 has an Integer Overflow.

libfreerdp/gdi/gdi.c in FreeRDP > 1.0 through 2.0.0-rc4 has an Out-of-bounds Read.

libfreerdp/codec/planar.c in FreeRDP version > 1.0 through 2.0.0-rc4 has an Out-of-bounds Write.

A signal access-control issue was discovered in the Linux kernel before 5.6.5, aka CID-7395ea4e65c2. Because exec_id in include/linux/sched.h is only 32 bits, an integer overflow can interfere with a do_notify_parent protection mechanism. A child process can send an arbitrary signal to a parent process in a different security domain. Exploitation limitations include the amount of elapsed time before an integer overflow occurs, and the lack of scenarios where signals to a parent process present a substantial operational threat.

In FreeRDP after 1.1 and before 2.0.0, a stream out-of-bounds seek in rdp_read_font_capability_set could lead to a later out-of-bounds read. As a result, a manipulated client or server might force a disconnect due to an invalid data read. This has been fixed in 2.0.0.

In FreeRDP after 1.1 and before 2.0.0, there is an out-of-bound read of client memory that is then passed on to the protocol parser. This has been patched in 2.0.0.