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CVE-2026-53277
KVM: arm64: Take the SRCU lock for page table walks in fault injection and AT emulation
Published 2026-06-25 (4 months ago) by the Linux kernel CNA. Subsystem arch/arm64. Debian urgency: unimportant.
What to do, per Debian release
Debian's own status for CVE-2026-53277 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 | vulnerable | 6.12.113-1 | No fix published anywhere yet, neither in Debian nor upstream for the series trixie tracks. Watch the Debian tracker page for this CVE. Advisories for trixie have historically landed a median of 11 days after publication. |
| Debian 14forky | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
| Debian unstablesid | fixed | 7.0.13-1 | Update the kernel and reboot. Fixed in 7.0.13-1. A running kernel keeps the old code until the machine restarts. |
The vulnerability
What the bug is
walk_s1() and kvm_walk_nested_s2() expect to be called while holding kvm->srcu to guard against memslot changes. While this is generally the case, __kvm_at_s12() and __kvm_find_s1_desc_level() call into the respective walkers without taking kvm->srcu. Fix by acquiring kvm->srcu prior to the table walk in both instances.
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/arm64/kvm/at.c
- What this is
- KERNEL VIRTUAL MACHINE FOR ARM64 (KVM/arm64)MAINTAINERS section matched on arch/arm64/kvm/ · linux-arm-kernel@lists.infradead.org · Maintained
- Kernel module
- kvm
Check it on the machine
grep -w CONFIG_KVM /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.
lsmod | grep -w kvmPrints a line if that module is loaded right now, and nothing if it is not. One that is not loaded can still be loaded later by anything that needs it.
Show whether Debian builds this, per release
Debian builds this, but not on every flavour. At least one release below builds the code on some of its kernel flavours and not on others, so the answer depends on the architecture and flavour installed. The build rule could not be established for 1 release, so nothing is claimed about those.
- bookworm?
- trixieBnot built on armel/rpi, armhf/armmp, armhf/armmp-lpae, armhf/rt/armmp
- forky, sidBnot built on armhf/armmp, armhf/armmp-lpae
- ?
- not established - no Makefile entry for the affected file
- B
- built in on some, a module on others, absent on the rest
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_KVM
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
- 2026-06-25 (4 months ago)source
- CVSS
- 8.8 high
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:Hsource recompute it - Attack vector
- local (AV:L)source
- EPSS
- 0.11%, higher than 1.1% of all CVEssource
- CISA KEV
- not listedthe KEV catalogue
- Debian urgency
- unimportantsource
- Subsystem
- arch/arm64
Upstream fixes
The versions the CNA records as introducing and fixing this, and the commit for each. source
| Introduced | Fixed in | Commit |
|---|---|---|
| 6.12 | 6.18.36 | 97706097f9b8 |
| 6.12 | 7.0.13 | ec42b4ed1b07 |
| 6.12 | 7.1 | f2ca45b50d42 |
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
- The vulnerable KVM arm64 page-table walks are reached through local KVM execution paths, including `KVM_RUN` handling of trapped AT instructions and guest abort injection, not through network input. An attacker needs local ability to create/control a KVM VM or vCPU context.
- AC:LAttack complexity, low
- The race is attacker-controllable because one thread can drive the vCPU path into the AT/S1PTW page-table walk while another thread mutates memslots with `KVM_SET_USER_MEMORY_REGION`. Nested virtualization support and memslot updates are reasonable KVM deployment conditions, not fragile external prerequisites.
- PR:LPrivileges required, low
- The attacker needs access to KVM device/file descriptors or equivalent VM control, but the relevant ioctls do not require host root or a special capability once `/dev/kvm` access is available. This is therefore low privilege rather than high privilege.
- UI:NUser interaction, none
- No separate victim action is required after the attacker controls the KVM VM/vCPU and the racing memslot operation. The trigger is programmatic through guest execution and KVM ioctls.
- S:CScope, changed
- The bug is in host KVM handling of guest-controlled translation state, and exploitation can affect the host kernel/hypervisor outside the guest security boundary. KVM guest/VMM-to-host impact is a changed-scope scenario.
- C:HConfidentiality impact, high
- The missing SRCU lock permits stale or freed memslot data to be used during `kvm_read_guest()` and descriptor updates, creating a use-after-free style memory safety issue. Under the required conservative scoring, this can support high-impact information disclosure.
- I:HIntegrity impact, high
- The affected walks can also update guest page-table descriptors and dirty-log state through stale memslot-derived pointers, giving a plausible kernel memory corruption/write surface. Use-after-free style corruption is scored as high integrity impact.
- A:HAvailability impact, high
- At minimum, dereferencing stale memslot structures or dirty bitmap pointers can crash or oops the host kernel. A host kernel crash is high availability impact.