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CVE-2026-72181
mips: sched: Fix CPUMASK_OFFSTACK memory corruption
Published 2026-08-15 (2 months ago) by the Linux kernel CNA. Subsystem arch/mips. Debian urgency: not yet assigned.
Debian does not build this code. The per-release build detail is under "Where it lives" below.
What to do, per Debian release
Debian's own status for CVE-2026-72181 in every release this site tracks, and what each one means in practice. Every status below is the one the Debian Security Team publishes for this CVE. source
| Release | Status | Version | What this means |
|---|---|---|---|
| Debian 12bookworm | fixed | 6.1.180-1 | Update the kernel and reboot. Fixed in 6.1.180-1. A running kernel keeps the old code until the machine restarts. |
| Debian 13trixie | fixed | 6.12.100-1 | Update the kernel and reboot. Fixed in 6.12.100-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.1.5-1 | Update the kernel and reboot. Fixed in 7.1.5-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
This patch addresses a critical memory management flaw. When CONFIG_CPUMASK_OFFSTACK is enabled, cpumask_var_t is a pointer. Consequently, sizeof(new_mask) evaluates to the pointer size, causing copy_from_user() to clobber the mask pointer. Furthermore, the old logic performed copy_from_user() before allocating the mask. Fix this by allocating new_mask first. To handle variable-sized user masks correctly, use cpumask_size() to truncate overly large user masks or pad undersized masks with zeros before copying the data directly into the allocated buffer.
Where it lives
The fix touches these files. If the subsystem is one you do not use, the practical exposure is lower, though the package is still the vulnerable one.
arch/mips/kernel/mips-mt-fpaff.c
- What this is
- MIPSMAINTAINERS section matched on arch/mips/ · linux-mips@vger.kernel.org · Maintained
- Kernel module
- none to look for. The file would have gone into mips_mt_fpaff, and Debian does not compile it into that module, so finding mips_mt_fpaff in lsmod would say nothing about this CVE.
Check it on the machine
grep -w CONFIG_MIPS_MT_FPAFF /boot/config-$(uname -r)Reads the booted kernel's own configuration, on the machine and nowhere else. =y is built in, =m is a module, and an is not set line means the code is not there.
Show whether Debian builds this, per release
Debian does not build this code. In 4 releases below, every kernel flavour Debian publishes has the switch off, so the vulnerable file is compiled into no kernel binary Debian ships.
- bookworm, trixie, forky, sidn
- n
- not enabled on any flavour - this release does not build the code
- Build switch
- CONFIG_MIPS_MT_FPAFF
From the configuration Debian publishes for every kernel flavour it builds. It covers only the architectures Debian ships a linux-config package for, and nothing about a kernel you built yourself. Debian's own status above stays authoritative about the source package.MAINTAINERS kbuild Makefiles Debian linux-config packages
Signals
- Published
- 2026-08-15 (2 months ago)source
- CVSS
- 7.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.16%, higher than 5.3% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- not yet assignedsource
- Subsystem
- arch/mips
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 2.6.23 | 5.10.265 | 2f7730c03a9d |
| 2.6.23 | 5.15.212 | d20ee42f8226 |
| 2.6.23 | 6.1.178 | 15ba8053fe41 |
| 2.6.23 | 6.6.145 | 3446ffb5d03c |
| 2.6.23 | 6.12.97 | 87a56c1e8e36 |
| 2.6.23 | 6.18.40 | 1caee6e084a9 |
| 2.6.23 | 7.1.5 | a1dd41d00c57 |
| 2.6.23 | 7.2 | 98e37db4a34d |
Why the CNA scored it this way
Quoted from the kernel CNA's own scoring file, word for word. A highlighted metric carries the most severe value CVSS v3.1 defines for it, which is what pushes the score up. source
- AV:LAttack vector, local
- Exploitation requires invoking the sched_setaffinity syscall on a MIPS o32 kernel; the vulnerable mipsmt_sys_sched_setaffinity handler is only wired into the o32 syscall table and is not reachable from remote network protocols.
- AC:LAttack complexity, low
- On affected builds the attacker reliably triggers the flaw with a single sched_setaffinity syscall supplying a user buffer; no races, special victim state, or uncontrollable memory layout are required beyond calling the syscall with attacker-chosen mask bytes.
- PR:LPrivileges required, low
- Any unprivileged local user can call sched_setaffinity; the corrupting copy_from_user runs before check_same_owner/CAP_SYS_NICE, and setting affinity on one's own process needs no special capabilities beyond normal local execution.
- UI:NUser interaction, none
- Exploitation requires only a direct sched_setaffinity syscall from the attacker; no victim interaction such as opening files, clicking links, or mounting filesystems is needed.
- S:UScope, unchanged
- The vulnerability corrupts kernel stack/scheduler state within the same kernel security domain; it does not cross a VM, container, or IOMMU boundary on its own.
- C:HConfidentiality impact, high
- Misplaced copy_from_user clobbers a kernel stack pointer with attacker-controlled bytes, and the never-initialized kmalloc cpumask can be stored in user_cpus_allowed and leaked back to userspace via sched_getaffinity.
- I:HIntegrity impact, high
- The bug is a kernel memory corruption from writing attacker-controlled data to the wrong address (the cpumask pointer on the stack) before allocation, which is an out-of-bounds-style write primitive in kernel context.
- A:HAvailability impact, high
- Kernel memory corruption in the sched_setaffinity path can cause oops, panic, or wedged scheduling/affinity state; corrupted stack data and misuse of uninitialized cpumask contents can crash or hang the system.