# CVE-2026-90616 — Flatpak

> As of 2026-09-12, CVE-2026-90616 is a HIGH-severity vulnerability in Flatpak, CVSS v3.1 7.4. No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-90616 as of 2026-09-12; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-12

## What is CVE-2026-90616?

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.

The record classifies CVE-2026-90616 under weakness class [CWE-61](https://cwe.mitre.org/data/definitions/61.html). Its CVSS v3 base vector states that the flaw requires local access to the host, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 23 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.4 — HIGH (`CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 3.7/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-12

## Is CVE-2026-90616 being exploited?

It currently carries a trending score of 30 in the Threadlinqs vulnerability feed.

## Affected products and versions

- **Flatpak**: Flatpak

## How to fix CVE-2026-90616

No vendor patch reference has been recorded for CVE-2026-90616 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-90616

No threat campaign in the Threadlinqs corpus currently references CVE-2026-90616, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD. Last verified by Threadlinqs on 2026-09-14. This product uses the NVD API but is not endorsed or certified by the NVD.

**Other references**

- [github.com](https://github.com/flatpak/flatpak/security/advisories/GHSA-8688-9x26-hhxj)
- [openwall.com](https://www.openwall.com/lists/oss-security/2026/08/11/9)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-90616
Full detection coverage and IOCs for threats exploiting CVE-2026-90616 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp