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

No CVE ID is currently available. Please reference as
GHSA-pxhw-h44j-8pfx until we have a CVE ID.

As previously discussed with the security team, fixing this in versions
older than 0.12.0 does not look feasible, so I'm going to prepare a
backport of 0.12.0 to stable.

    smcv

We believe that the bug you reported is fixed in the latest version of
bubblewrap, which is due to be installed in the Debian FTP archive.

A summary of the changes between this version and the previous one is
attached.

Thank you for reporting the bug, which will now be closed.  If you
have further comments please address them to 1145655@bugs.debian.org,
and the maintainer will reopen the bug report if appropriate.

Debian distribution maintenance software
pp.
Simon McVittie <smcv@debian.org> (supplier of updated bubblewrap package)

(This message was generated automatically at their request; if you
believe that there is a problem with it please contact the archive
administrators by mailing ftpmaster@ftp-master.debian.org)
Format: 1.8
Date: Wed, 26 Aug 2026 11:32:16 +0100
Source: bubblewrap
Architecture: source
Version: 0.12.0-1
Distribution: unstable
Urgency: high
Maintainer: Utopia Maintenance Team <pkg-utopia-maintainers@lists.alioth.debian.org>
Changed-By: Simon McVittie <smcv@debian.org>
Closes: 1145655
Changes:
 bubblewrap (0.12.0-1) unstable; urgency=high
 .
   * New upstream release
     - Prevent sandbox escape via symlink traversal.
       If an app framework such as Flatpak mounts subdirectories into a
       directory controlled by the sandboxed app, a malicious or compromised
       sandboxed app could create symlinks in that directory to arrange for
       files/directories to be created on the host system.
       (GHSA-pxhw-h44j-8pfx, no known CVE ID; Closes: #1145655)
     - d/rules: Stop passing -Dsupport_setuid=false.
       The option no longer exists, and the new version of bubblewrap always
       behaves as though its value was false.
     - d/copyright: Update license from LGPL-2+ to LGPL-2.1+, matching upstream
     - d/p/debian/Change-EPERM-error-message-to-show-Debian-specific-inform.patch:
       Adjust patch to apply to the new upstream release
   * d/rules: Don't compile fallback code paths for kernel older than 5.10.
     This ensures that we're using the safest available mechanisms,
     using the openat2() syscall rather than emulating it in user-space.
     As a result, this version will not work on kernels older than the
     one found in Debian 11.
Checksums-Sha1:
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 183eaff6b078c1ea5ad55271e7d1fa5c8c0d339e 126452 bubblewrap_0.12.0.orig.tar.xz
 5a2bfd116f752cadb6c21ca2e48646bb97dcfb2c 13092 bubblewrap_0.12.0-1.debian.tar.xz
 5dfd9cab67a11e66f92a1316510eee7599591f67 7139 bubblewrap_0.12.0-1_source.buildinfo
Checksums-Sha256:
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 9760d007363e3abba7c747489910f9f82d9fca53ba3bd3282e396fa3c97a3314 126452 bubblewrap_0.12.0.orig.tar.xz
 60691fa8488db2de4dd19d59fb0b084e692695c38616dcf8e20b08a4d372ab93 13092 bubblewrap_0.12.0-1.debian.tar.xz
 65322f643cfcd5b05b63231055655f62f860b2e84d4e4eb681a9d2047cb4aef6 7139 bubblewrap_0.12.0-1_source.buildinfo
Files:
 9652e93e58dd3c2c5a9a631d6f4775fe 2427 admin optional bubblewrap_0.12.0-1.dsc
 323b059c9599b60b456bcf9e9800ff44 126452 admin optional bubblewrap_0.12.0.orig.tar.xz
 255ccb24268c5460325edced14f15c9d 13092 admin optional bubblewrap_0.12.0-1.debian.tar.xz
 32130cf24c6258998317dbc4e3b634c4 7139 admin optional bubblewrap_0.12.0-1_source.buildinfo
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<https://people.debian.org/~smcv/temp/2026/bubblewrap-bug1145655/>
(debdiffs included, bubblewrap_0.12.0-1~deb13u1_debianonly.diff is
filtered to debian/ only)

A functionally equivalent test-build (differing only in the changelog)
is in
<https://people.debian.org/~smcv/temp/2026/bubblewrap-bug1145655/rc/>.

For the upstream changes, the easiest thing to review is likely to be:

git log -p --reverse --stat --ignore-space-change v0.11.0..v0.12.0

Some notes:

* commit ea185f6fb135782cabab342e33432e8482a2f5c9 "Inline the privileged
   ops" is rather noisy, unfortunately, but we've been using a version with
   that commit for a while in the Steam Runtime with no regressions
   reported.

* In commit 67d4be103b18706b5b4e3f495daa35e89e47b163 "Import safe_openat()
   from crun", as a result of -Dassume_kernel=5.10.0 we don't ever call
   chroot_realpath(), and looking for "%s%s%s" in strings(1) output confirms
   that it doesn't even get linked. This is good, because the
   implementation of chroot_realpath() scares me (far too much strcat()).
   We can confirm this with:

   $ bwrap --dev-bind / / true
   (exit 0, no output)
   $ bwrap --debug-opt=force-openat-fallback --dev-bind / / true
   bwrap: Can't open source /: Function not implemented

   (--debug-opt=force-openat-fallback emulates a pre-5.6 kernel where
   openat2() failed.)

If the security team is happy with this, there is a signed .changes in
<https://people.debian.org/~smcv/temp/2026/bubblewrap-bug1145655/bubblewrap_0.12.0-1~deb13u1_source.tar.gz.gpg>
(encrypted to the security team's key) which should be suitable for
upload to security-master, to save a round-trip from security team
approval to me uploading; or I can upload it myself if the team would
prefer that. I have also pushed the changes to
<https://salsa.debian.org/debian/bubblewrap/-/tree/debian/trixie-proposed?ref_type=heads>
and will copy that to the debian/trixie branch if accepted.

Thanks,
     smcv