Systemd: systemd-tmpfiles symlink-redirected arbitrary file overwrite via a chase_safe root-to-unprivileged ownership transition bypass
Summary
| CVE | CVE-2026-16552 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-22 16:17:16 UTC |
| Updated | 2026-07-22 17:16:55 UTC |
| Description | A flaw was found in systemd-tmpfiles. When processing a tmpfiles.d configuration entry that writes to a file, systemd-tmpfiles can follow a symbolic link placed by an unprivileged local user, and an existing safety check does not detect this specific case because it always treats transitions away from the root user as safe. On systems where a tmpfiles.d configuration targets a path an unprivileged user can influence, this could allow that user to redirect a privileged systemd-tmpfiles write to a file of their choosing, though the content written remains determined by the existing configuration rather than by the unprivileged user. The highest threat from this vulnerability is to integrity. |
Risk And Classification
Primary CVSS: v3.1 6.3 MEDIUM from [email protected]
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
Problem Types: CWE-59 | CWE-59 Improper Link Resolution Before File Access ('Link Following')
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 6.3 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H |
| 3.1 | CNA | CVSS | 6.3 | MEDIUM | CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H |
CVSS v3.1 Breakdown
Attack Vector
LocalAttack Complexity
HighPrivileges Required
LowUser Interaction
NoneScope
UnchangedConfidentiality
NoneIntegrity
HighAvailability
HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Hardened Images | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53... | [email protected] | github.com | |
| github.com/systemd/systemd/blob/b9ef5951f8f9e156479494fdb9ca6274cb3d3c53... | [email protected] | github.com | |
| access.redhat.com/security/cve/CVE-2026-16552 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank İbrahim Sağlam (Eresus Security) for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-06-05T23:12:44.000Z | Reported to Red Hat. |
| CNA | 2026-07-22T00:00:00.000Z | Made public. |
Workarounds
CNA: Restrict or audit any custom tmpfiles.d configuration entries (e.g. authored via configuration-management tooling) that use the 'w' item type against paths under /run/user/*, per-user home directories, or other locations where an unprivileged user can influence path resolution, until an upstream fix is available.
There are currently no legacy QID mappings associated with this CVE.