CVE-2026-96808
In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers,…
- Published
- Updated
- Reserved
- Assigned by
- mitre
Description
In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.
Timeline
ID reserved
By mitre
Published
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| mitreCNA (assigner) | 3.1 | High7.4 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVDNVD · Awaiting Analysis | 3.1 | High7.4 | CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.11% · top 98% of all CVEs (7 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.4.
Weakness
Affected products
What to do
Solution: Fixed in 1.18.1 by commits: * a3583bc https://github.com/flatpak/flatpak/commit/a3583bc87d4f86c2794ff879ea56fce95b0b0b5f "revokefs: Avoid symlink path traversal out of basefd in simple cases" * b00c7b5 https://github.com/flatpak/flatpak/commit/b00c7b5073a25bdc34653642de543b5ef6fe0225 "revokefs: Avoid symlink path traversal in link(), rename()" * 4ddb5dc https://github.com/flatpak/flatpak/commit/4ddb5dc0de1bd25e52627f520a49063d94f79377 "revokefs: Avoid symlink path traversal in symlink()" * e7f96b4 https://github.com/flatpak/flatpak/commit/e7f96b4d1533f735ace2ea21dbf770e8d4be465a "revokefs: Avoid symlink path traversal in chmod()" For LTS operating system distributions, backports of these changes are available in the flatpak-1.16.x branch.
References (1)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-96808)Record last updated .