Re: Flatpak 1.18.1 fixes multiple vulnerabilities
Simon McVittie disclosed CVE identifiers for multiple vulnerabilities fixed in Flatpak 1.18.1, with two IDs still pending from MITRE.
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Vulnerability2 · 1 read
CVE-2026-96279
Hardlink file disclosure in Flatpak OCI app installs
- CVSS 3.1
- 6.5 medium
- EPSS
- —
- Published
- ·
- Modified
AI analysisSummaries by Vani AI
A malicious OCI registry can make Flatpak hardlink arbitrary host files into the extraction directory when a user installs or updates an application from that OCI remote. Those links can disclose the contents of any host file the installing user can read, including sensitive files such as /etc/shadow when a system-wide install runs as root. The issue is improper link resolution (CWE-59), scored CVSS 3.1 6.5 (medium): network attack, low complexity, no privileges required, user interaction required, high confidentiality impact, and no integrity or availability impact. Users of affected Flatpak versions who add or refresh apps from OCI remotes are in scope; ordinary OSTree remotes are not this trigger. No public proof-of-concept is known and the CVE is not on the CISA KEV list; Flatpak 1.18.1 is reported to fix it among other vulnerabilities.
What to do: Upgrade Flatpak to 1.18.1 or later. Until then, do not install or update apps from untrusted OCI remotes, and review configured remotes for unexpected OCI sources. Treat system-wide installs run as root as higher risk, because readable host files such as /etc/shadow can be disclosed.
| Product | Affected |
|---|---|
| Flatpak project Flatpak | Versions before 1.18.1 (1.18.1 reported to fix this; exact lower bound not stated in the source data) |
Estimated exposure
largeHundreds of thousands to low millions of Flatpak installations; a smaller subset that uses OCI remotes is practically exposed — Flatpak ships by default on Fedora and is widely packaged on other Linux distributions and devices, so total installs are plausibly in the hundreds of thousands to millions, but no install census is in the CVE data and the bug is only…
Order-of-magnitude estimate by the model from install counts, market share and public scan data it knows; verify before quoting.
Description · NVD
A malicious OCI registry can hardlink arbitrary host files into the extraction directory when a user installs or updates a Flatpak application from an OCI remote, allowing disclosure of arbitrary host file contents. For system-wide installs running as root, this includes sensitive files such as /etc/shadow.
- Weakness
- CWE-59
- Vector
- CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N