Flatpak releases 1.18.1, fixing critical sandbox escape and nine other flaws
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Flatpak releases version 1.18.1, patching a critical sandbox escape flaw and nine other vulnerabilities. The flaw allowed a malicious sandboxed app to gain read/write access to host files and potentially execute code. Major distributions, including Fedora, have not yet shipped the update to stable releases.
The Critical Flaw
The critical vulnerability stems from missing symlink protection in Flatpak. A malicious sandboxed app can replace its private directories with symlinks pointing to host locations such as the user's home folder, which are then mounted inside the sandbox. The GitHub advisory warns this allows arbitrary read and write access to host files and can be escalated to arbitrary code execution. Flatpak 1.18.1 fixes the flaw, which is one of ten vulnerabilities addressed in the release.
Additional Vulnerabilities
Nine other severe Flatpak flaws were fixed in version 1.18.1, according to the oss-security mailing list. Path traversal bugs allow privilege escalation to root, arbitrary root file reads and writes, and downgrades of system apps to older vulnerable versions. Maintainers warn all older Flatpak versions are believed vulnerable and urge users to upgrade to 1.18.1 or prerelease 1.19.0. Red Hat has assigned CVE numbers to two of the ten issues; the rest have requested IDs.
Distribution Exposure
Major Linux distributions that bundle Flatpak by default, such as Fedora, have yet to push version 1.18.1 to stable releases. Users remain exposed until those updates arrive. The disclosure follows earlier sandbox escape flaws, including CVE-2026-34078, disclosed in April with a 10 out of 10 severity score from the National Vulnerability Database.
What's Next
Fedora and other distributions are expected to push Flatpak 1.18.1 to stable repositories in the coming days, though no timeline has been announced. It remains unclear how many users have already applied the update and whether the sandbox escape has been exploited in the wild.
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Flatpak releases 1.18.1, fixing critical sandbox escape and nine other flaws
