Amazon Linux 2023 Security Advisory: ALAS2023-2026-3143
Advisory Released Date: 2026-09-29
Advisory Updated Date: 2026-09-29
A flaw was found in Flatpak. A Time-of-check to time-of-use (TOCTOU) race condition exists in the `org.freedesktop.Flatpak.SystemHelper` component. This vulnerability occurs because a privileged `chmod` operation executes before the OSTree repository validation within the `Deploy()` function. An attacker can exploit this timing window to redirect symlinks to arbitrary files, potentially leading to unauthorized file manipulation or information disclosure. (CVE-2026-76925)
In Flatpak before 1.18.1, a malicious sandboxed app can obtain arbitrary read and write access to files on the host, which can be escalated to arbitrary code execution on the host, a different vulnerability than CVE-2026-76925. Flatpak creates a few app data directories (e.g., /var/cache, /var/data, /var/config, and /var/tmp) in every sandbox on every app launch where, in some cases, components of the path are attacker-controlled. Missing symlink protection can redirect the directories. Some of these directories are bind-mounted by Flatpak by passing the path (e.g., /home/user/.var/app/APP_ID/cache/tmp), which contains attacker-controlled directories (tmp) to bwrap --bind SRC DST. bwrap passes the path on to the kernel, which then follows symlinks. A malicious symlink can point to arbitrary locations on the host and it will become mounted inside the sandbox. (CVE-2026-90616)
Affected Packages:
flatpak
Issue Correction:
Run dnf update flatpak --releasever 2023.12.20260928 or dnf update --advisory ALAS2023-2026-3143 --releasever 2023.12.20260928 to update your system.
More information on how to update your system can be found on this page: Amazon Linux 2023 documentation
aarch64:
flatpak-debuginfo-1.18.1-1.amzn2023.aarch64
flatpak-libs-debuginfo-1.18.1-1.amzn2023.aarch64
flatpak-session-helper-1.18.1-1.amzn2023.aarch64
flatpak-devel-1.18.1-1.amzn2023.aarch64
flatpak-session-helper-debuginfo-1.18.1-1.amzn2023.aarch64
flatpak-libs-1.18.1-1.amzn2023.aarch64
flatpak-tests-1.18.1-1.amzn2023.aarch64
flatpak-1.18.1-1.amzn2023.aarch64
flatpak-tests-debuginfo-1.18.1-1.amzn2023.aarch64
flatpak-debugsource-1.18.1-1.amzn2023.aarch64
noarch:
flatpak-selinux-1.18.1-1.amzn2023.noarch
src:
flatpak-1.18.1-1.amzn2023.src
x86_64:
flatpak-debuginfo-1.18.1-1.amzn2023.x86_64
flatpak-libs-debuginfo-1.18.1-1.amzn2023.x86_64
flatpak-session-helper-debuginfo-1.18.1-1.amzn2023.x86_64
flatpak-debugsource-1.18.1-1.amzn2023.x86_64
flatpak-devel-1.18.1-1.amzn2023.x86_64
flatpak-session-helper-1.18.1-1.amzn2023.x86_64
flatpak-1.18.1-1.amzn2023.x86_64
flatpak-tests-debuginfo-1.18.1-1.amzn2023.x86_64
flatpak-libs-1.18.1-1.amzn2023.x86_64
flatpak-tests-1.18.1-1.amzn2023.x86_64