CVE-2026-87766

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

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.

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Bubblewrap (/usr/bin/bwrap) is a core execution engine for unprivileged containers that works as a setuid binary on kernels without user namespaces.

Security Fix(es):

• bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup (CVE-2026-87766)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

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.

• SECURITY UPDATE: symlink traversal during sandbox setup lets a crafted source tree redirect file/dir creation and mounts outside the sandbox (sandbox escape)
  • debian/patches/CVE-2026-87766.patch: resolve every destination inside /newroot and every source inside /oldroot a component at a time (safe_openat in utils.c), create and mount through O_PATH|O_NOFOLLOW fds passed to the privileged helper (bind_mount_fd), and refuse to mount on a symlink destination (bubblewrap.c, bind-mount.c, utils.c)
  • CVE-2026-87766

Sandbox escape: symlink traversal via /oldroot allows writing files outside sandbox during setup

These are all security issues fixed in the flatpak-1.18.3-1.1 package on the GA media of openSUSE Tumbleweed.

It was discovered that Bubblewrap incorrectly handled certain temporary directories. A local attacker could possibly use this issue to cause a denial of service or execute arbitrary code. This issue only affected Ubuntu 18.04 LTS. (CVE-2019-12439)

It was discovered that Bubblewrap incorrectly handled certain symlinks during sandbox setup. A local attacker could possibly use this issue to create files outside of the sandbox. (CVE-2026-87766)