Public bug reported:
System Environment:
* OS: Ubuntu 26.04 (Upgraded from 25.10)
* Kernel: Linux 7.0.0-15-generic
* Snapd Version: 2.75.2+ubuntu26.04.2
* Affected App: Obsidian (and potentially any Electron/Classic snap built on
core20 base)
Bug Description:
When attempting to launch a classic snap that relies on the core20 base (e.g.,
Obsidian) as a normal unprivileged user via GUI desktop icon or
/snap/bin/obsidian, the application silently terminates without any graphical
output or logs.
However, the application launches and runs perfectly fine under two
specific conditions:
1. Running with root privileges: sudo obsidian
2. Executing the raw binary directly by bypassing the snap wrapper:
/snap/obsidian/current/obsidian
Root Cause Analysis (from strace tracking):
An strace -f logs tracking the process execution reveals that the crash happens
during the very early stage of the setuid transition inside snap-confine. The
execution chain stops abruptly right after execve targets snap-confine:
```
execve("/usr/lib/snapd/snap-confine", ["/usr/lib/snapd/snap-confine",
"--classic", "--base", "core20", "snap.obsidian.obsidian", ...]) = 0
access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
openat(AT_FDCWD, "/etc/ld.so.cache", O_RDONLY|O_CLOEXEC) = 3
... [Process forcefully terminated / SIGABRT right here before loading libc]
```
This indicates a critical security policy deadlock or an environment
sanity checking failure in AppArmor/glibc on Ubuntu 26.04. When an
unprivileged user triggers snap-confine with --classic mode under a
legacy core20 runtime environment, the newly hardened user namespace
restrictions or strict setuid environment scrubbing in Ubuntu 26.04
silently kills the wrapper process before it can even parse ld.so.cache
or initialize standard error logging.
** Affects: snapd (Ubuntu)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2154730
Title:
snap-confine crashes instantly (silent abort) on Ubuntu 26.04 when
launching classic snaps with core20 base as unprivileged user
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