# CVE-2026-87766: Bubblewrap: bubblewrap: symlink traversal via /oldroot allows writing files outside sandbox during setup

Status: published. Published: 2026-09-09. Updated: 2026-11-02.

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.

## Remediation

- workaround: Do not create files on untrusted content with unpatched bwrap. Do not install untrusted Flatpaks. No upstream fix for older setuid builds. (source: CNA: redhat)

## Affected products and versions

- Red Hat / Red Hat Enterprise Linux 10 (bubblewrap): ≥ 0:0.10.0-5.el10_2; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 10.0 Extended Update Support (bubblewrap): ≥ 0:0.10.0-3.el10_0.4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8 (bubblewrap): ≥ 0:0.4.0-3.el8_10; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support (bubblewrap): ≥ 0:0.4.0-3.el8_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On (bubblewrap): ≥ 0:0.4.0-3.el8_4; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support (bubblewrap): ≥ 0:0.4.0-3.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On (bubblewrap): ≥ 0:0.4.0-3.el8_6; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Telecommunications Update Service (bubblewrap): ≥ 0:0.4.0-3.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions (bubblewrap): ≥ 0:0.4.0-3.el8_8; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9 (bubblewrap): ≥ 0:0.6.3-1.el9_8.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions (bubblewrap): ≥ 0:0.4.1-7.el9_2.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions (bubblewrap): ≥ 0:0.4.1-7.el9_4.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Enterprise Linux 9.6 Extended Update Support (bubblewrap): ≥ 0:0.4.1-8.el9_6.1; < * (unaffected, rpm). Source: CNA: redhat
- Red Hat / Red Hat Hardened Images (bubblewrap): Version range not reported. Source: CNA: redhat

## Severity and prioritization

- CVSS 3.1: 8.8 (high); CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H; source: CNA: redhat

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-01; percentile 11.43%

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-59

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://access.redhat.com/errata/RHSA-2026:85306 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85308 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85309 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85312 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85313 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85317 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85319 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85322 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85324 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/errata/RHSA-2026:85325 (CNA: redhat; vendor-advisory, x_refsource_REDHAT)

- https://access.redhat.com/security/cve/CVE-2026-87766 (CNA: redhat; vdb-entry, x_refsource_REDHAT)

- https://bugs.debian.org/1145655 (CNA: redhat)

- https://bugzilla.redhat.com/show_bug.cgi?id=2530542 (CNA: redhat; issue-tracking, x_refsource_REDHAT)

- https://github.com/containers/bubblewrap/releases/tag/v0.12.0 (CNA: redhat)

- https://github.com/containers/bubblewrap/security/advisories/GHSA-pxhw-h44j-8pfx (CNA: redhat)

- https://www.openwall.com/lists/oss-security/2026/08/27/7 (CNA: redhat)

- http://www.openwall.com/lists/oss-security/2026/09/09/3 (ADP: CVE)

- http://www.openwall.com/lists/oss-security/2026/09/22/23 (ADP: CVE)

## Provenance

- CNA: redhat: https://www.cve.org/CVERecord?id=CVE-2026-87766; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-87766; retrieved 2026-11-02; source updated Not reported

Revision: e0fb2b0e8ea171a31083f87b7bef6fd7388f00ccc2726a62c740770099ec809d

Canonical: https://y2.dev/cve/CVE-2026-87766

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