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

CVE-2026-87766 is fixed in 3 products on 1 platform, first by RHSA-2026:85312, released September 9, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-87766
- Priority: High
- CVSS: 8.8 (Important)
- EPSS: 0.0021
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 9, 2026
- Weakness: Improper Link Resolution Before File Access ('Link Following')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-87766

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | bubblewrap Debian 13.5 (trixie) | 0.12.0-1~deb13u1 | [DEBIAN-CVE-2026-87766](https://patchblox.com/security/data/fix/linux/debian-cve-2026-87766.md) | Sep 10, 2026 |
| Linux | bubblewrap Debian 14 | 0.12.0-1 | [DEBIAN-CVE-2026-87766](https://patchblox.com/security/data/fix/linux/debian-cve-2026-87766.md) | Sep 10, 2026 |
| Linux | bubblewrap RHEL 10 | 0.10.0-3.el10_0.4 | [RHSA-2026:85312](https://patchblox.com/security/data/fix/linux/rhsa-2026-85312.md) | Sep 9, 2026 |
| Linux | bubblewrap RHEL 8 | 0:0.4.0-3.el8_10 | [RHSA-2026:85306](https://patchblox.com/security/data/fix/linux/rhsa-2026-85306.md) | Oct 20, 2026 |
| Linux | bubblewrap RHEL 9 | 0:0.6.3-1.el9_8.1 | [RHSA-2026:85309](https://patchblox.com/security/data/fix/linux/rhsa-2026-85309.md) | Oct 20, 2026 |
| Linux | bubblewrap almalinux 10 | 0.10.0-5.el10_2 | [ALSA-2026:85308](https://patchblox.com/security/data/fix/linux/alsa-2026-85308.md) | Nov 7, 2026 |
| Linux | bubblewrap almalinux 8 | 0.4.0-3.el8_10 | [ALSA-2026:85306](https://patchblox.com/security/data/fix/linux/alsa-2026-85306.md) | Nov 7, 2026 |
| Linux | bubblewrap almalinux 9 | 0.6.3-1.el9_8.1 | [ALSA-2026:85309](https://patchblox.com/security/data/fix/linux/alsa-2026-85309.md) | Nov 7, 2026 |
| Linux | bubblewrap amzn 2023 | 0.12.0-1.amzn2023.0.1 | [ALAS2023-2026-3105](https://patchblox.com/security/data/fix/linux/alas2023-2026-3105.md) | Sep 28, 2026 |
| Linux | bubblewrap ol 10 | 0:0.10.0-5.el10_2 | [ELSA-2026-85308](https://patchblox.com/security/data/fix/linux/elsa-2026-85308.md) | Nov 7, 2026 |
| Linux | bubblewrap ol 8 | 0:0.4.0-3.el8_10 | [ELSA-2026-85306](https://patchblox.com/security/data/fix/linux/elsa-2026-85306.md) | Nov 7, 2026 |
| Linux | bubblewrap ol 9 | 0:0.6.3-1.el9_8.1 | [ELSA-2026-85309](https://patchblox.com/security/data/fix/linux/elsa-2026-85309.md) | Nov 7, 2026 |
| Linux | bubblewrap rocky 10 | 0:0.10.0-5.el10_2 | [RLSA-2026:85308](https://patchblox.com/security/data/fix/linux/rlsa-2026-85308.md) | Nov 7, 2026 |
| Linux | bubblewrap rocky 8 | 0:0.4.0-3.el8_10 | [RLSA-2026:85306](https://patchblox.com/security/data/fix/linux/rlsa-2026-85306.md) | Nov 7, 2026 |
| Linux | bubblewrap rocky 9 | 0:0.6.3-1.el9_8.1 | [RLSA-2026:85309](https://patchblox.com/security/data/fix/linux/rlsa-2026-85309.md) | Nov 7, 2026 |
| Linux | bubblewrap-debuginfo amzn 2023 | 0.12.0-1.amzn2023.0.1 | [ALAS2023-2026-3105](https://patchblox.com/security/data/fix/linux/alas2023-2026-3105.md) | Sep 28, 2026 |
| Linux | bubblewrap-debugsource amzn 2023 | 0.12.0-1.amzn2023.0.1 | [ALAS2023-2026-3105](https://patchblox.com/security/data/fix/linux/alas2023-2026-3105.md) | Sep 28, 2026 |

---

Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.