High · published May 15, 2026
In the Linux kernel, the following vulnerability has been resolved:
ptrace: slightly saner 'get_dumpable()' logic
The 'dumpability' of a task is fundamentally about the memory image of
the task - the concept comes from whether it can core dump or not - and
makes no sense when you don't have an associated mm.
And almost all users do in fact use it only for the case where the task
has a mm pointer.
But we have one odd special case: ptrace_may_access() uses 'dumpable' to
check various other things entirely independently of the MM (typically
explicitly using flags like PTRACE_MODE_READ_FSCREDS). Including for
threads that no longer have a VM (and maybe never did, like most kernel
threads).
It's not what this flag was designed for, but it is what it is.
The ptrace code does check that the uid/gid matches, so you do have to
be uid-0 to see kernel thread details, but this means that the
traditional "drop capabilities" model doesn't make any difference for
this all.
Make it all make a *bit* more sense by saying that if you don't have a
MM pointer, we'll use a cached "last dumpability" flag if the thread
ever had a MM (it will be zero for kernel threads since it is never
set), and require a proper CAP_SYS_PTRACE capability to override.
| Product | Versions | Fixed in |
|---|---|---|
| linux/linux_kernel | ≥ 3.16.52, < 3.17 | 3.17 |
| linux/linux_kernel | ≥ 4.4.40, < 4.5 | 4.5 |
| linux/linux_kernel | ≥ 4.8.16, < 4.9 | 4.9 |
| linux/linux_kernel | ≥ 4.9.1, < 5.10.256 | 5.10.256 |
| linux/linux_kernel | ≥ 5.11, < 5.15.207 | 5.15.207 |
| linux/linux_kernel | ≥ 5.16, < 6.1.173 | 6.1.173 |
| linux/linux_kernel | ≥ 6.2, < 6.6.139 | 6.6.139 |
| linux/linux_kernel | ≥ 6.7, < 6.12.89 | 6.12.89 |
| linux/linux_kernel | ≥ 6.13, < 6.18.31 | 6.18.31 |
| linux/linux_kernel | ≥ 6.19, < 7.0.8 | 7.0.8 |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| linux/linux_kernel | all versions | — |
| debian/debian_linux | all versions | — |