A flaw was found in bubblewrap. During sandbox setup, creating files or directories under the new root can follow a parent symlink onto the host via /oldroot, writing attacker-chosen paths outside the sandbox as the launching user. This happens before the sandboxed process starts. This issue is GHSA-pxhw-h44j-8pfx. It is fixed in bubblewrap 0.12.0.
Weakness
The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Bubblewrap | Ubuntu | esm-infra/bionic | * |
| Bubblewrap | Ubuntu | esm-infra/focal | * |
| Bubblewrap | Ubuntu | jammy | * |
| Bubblewrap | Ubuntu | noble | * |
| Bubblewrap | Ubuntu | resolute | * |
| Bubblewrap | Ubuntu | upstream | * |
Potential Mitigations
- Follow the principle of least privilege when assigning access rights to entities in a software system.
- Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/132.html
- https://cwe.mitre.org/data/definitions/17.html
- https://cwe.mitre.org/data/definitions/35.html
- https://cwe.mitre.org/data/definitions/76.html
References
- https://access.redhat.com/security/cve/CVE-2026-87766
- https://bugs.debian.org/1145655
- https://bugzilla.redhat.com/show_bug.cgi?id=2530542
- https://github.com/containers/bubblewrap/releases/tag/v0.12.0
- https://github.com/containers/bubblewrap/security/advisories/GHSA-pxhw-h44j-8pfx
- https://www.openwall.com/lists/oss-security/2026/08/27/7
- http://www.openwall.com/lists/oss-security/2026/09/09/3
- http://www.openwall.com/lists/oss-security/2026/09/22/23