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CVE-2026-64111
lsm: hold cred_guard_mutex for lsm_set_self_attr()
Published 2026-07-19 (3 months ago) by the Linux kernel CNA. Subsystem security. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-64111 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 | not affected | 6.1.190-1 | Nothing to do. bookworm never shipped the vulnerable code. |
| Debian 13trixie | fixed | 6.12.94-1 | Update the kernel and reboot. Fixed in 6.12.94-1. A running kernel keeps the old code until the machine restarts. |
| Debian 14forky | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.12-1 | Update the kernel and reboot. Fixed in 7.0.12-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
Just as proc_pid_attr_write() already does before calling the LSM hook. This only matters for SELinux and AppArmor which check whether the process is being ptraced and if so, whether to allow the transition.
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.
security/lsm_syscalls.c
- What this is
- SECURITY SUBSYSTEMMAINTAINERS section matched on security/ · linux-security-module@vger.kernel.org · Supported
Check it on the machine
grep -w CONFIG_SECURITY /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 builds this code. Every release with an answer below compiles the affected file into the kernels it ships. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixie, forky, sidy
- ?
- not established - no Makefile entry for the affected file
- y
- built into the kernel image on every flavour - only a patch removes it
Where a release above reads "not established", no build rule for the affected file was found in that release's kernel tree. That is a gap in this lookup, not a finding that the code is absent.
- Build switch
- CONFIG_SECURITY
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
- 2026-07-19 (3 months ago)source
- CVSS
- 7.1 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:Nsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.14%, higher than 2.7% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- security
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.8 | 6.12.92 | 82d3acee8859 |
| 6.8 | 6.18.34 | 5b906f31e977 |
| 6.8 | 7.0.11 | a010cadaf572 |
| 6.8 | 7.1 | 4a9b16541ad3 |
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 `lsm_set_self_attr` syscall (NR 460), which is strictly a local kernel entry point with no network, adjacent-wireless, or physical-device path to the vulnerable code.
- AC:LAttack complexity, low
- The bug is a TOCTOU race between `lsm_set_self_attr` and concurrent ptrace attach/detach; an attacker can control both the tracee thread issuing the syscall and a tracer thread (e.g., via fork/PTRACE_TRACEME), making the race reliably winnable without conditions outside attacker control.
- PR:LPrivileges required, low
- Any unprivileged local user can reach `sys_lsm_set_self_attr`; there is no capability or root requirement at the syscall boundary, and ptrace coordination is achievable within the same UID via standard unprivileged ptrace APIs.
- UI:NUser interaction, none
- Exploitation does not require any action from a separate victim user such as opening a file or mounting a filesystem; the attacker drives both the setattr syscall and the ptrace race directly.
- S:UScope, unchanged
- Successful exploitation changes the calling process's LSM credentials within the same kernel/OS security authority (SELinux domain or AppArmor profile transition), constituting standard local MAC bypass rather than crossing a VM, container-host, or IOMMU boundary.
- C:HConfidentiality impact, high
- Bypassing the ptrace-mediated transition check allows committing a new SELinux SID or AppArmor profile without tracer authorization, granting read access to data and resources denied under the prior confined context.
- I:HIntegrity impact, high
- The attack culminates in `commit_creds()` with an unauthorized LSM security context (SELinux `crsec->sid` or AppArmor label replacement), constituting arbitrary modification of the process's mandatory access control identity and associated permissions.
- A:NAvailability impact, none
- The vulnerability is a missing mutex enabling a policy-bypass race; it does not involve memory corruption, kernel oops, panic, hang, or other availability-impacting failure modes.