NVD / CVE Program· CNA Linux

CVE-2021-47341: KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
Fixed version: Linux Linux 069d44a24c0ff8f85adf49233aae7a8ca16f5c7e, 23fa2e46a5556f787ce2ea1a315d3ab93cced204, 5.10.52.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 069d44a24c0ff8f85adf49233aae7a8ca16f5c7e, 23fa2e46a5556f787ce2ea1a315d3ab93cced204, 5.10.52 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio BUG: KASAN: use-after-free in kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183 Read of size 8 at addr ffff0000c03a2500 by task syz-executor083/4269 CPU: 5 PID: 4269 Comm: syz-executor083 Not tainted 5.10.0 #7 Hardware name: linux,dummy-virt (DT) Call trace: dump_backtrace+0x0/0x2d0 arch/arm64/kernel/stacktrace.c:132 show_stack+0x28/0x34 arch/arm64/kernel/stacktrace.c:196 __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x110/0x164 lib/dump_stack.c:118 print_address_description+0x78/0x5c8 mm/kasan/report.c:385 __kasan_report mm/kasan/report.c:545 [inline] kasan_report+0x148/0x1e4 mm/kasan/report.c:562 check_memory_region_inline mm/kasan/generic.c:183 [inline] __asan_load8+0xb4/0xbc mm/kasan/generic.c:252 kvm_vm_ioctl_unregister_coalesced_mmio+0x7c/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:183 kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] el0_svc_common arch/arm64/kernel/syscall.c:158 [inline] do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220 el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367 el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383 el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670 Allocated by task 4269: stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121 kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track mm/kasan/common.c:56 [inline] __kasan_kmalloc+0xdc/0x120 mm/kasan/common.c:461 kasan_kmalloc+0xc/0x14 mm/kasan/common.c:475 kmem_cache_alloc_trace include/linux/slab.h:450 [inline] kmalloc include/linux/slab.h:552 [inline] kzalloc include/linux/slab.h:664 [inline] kvm_vm_ioctl_register_coalesced_mmio+0x78/0x1cc arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:146 kvm_vm_ioctl+0x7e8/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3746 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] invoke_syscall arch/arm64/kernel/syscall.c:48 [inline] el0_svc_common arch/arm64/kernel/syscall.c:158 [inline] do_el0_svc+0x120/0x290 arch/arm64/kernel/syscall.c:220 el0_svc+0x1c/0x28 arch/arm64/kernel/entry-common.c:367 el0_sync_handler+0x98/0x170 arch/arm64/kernel/entry-common.c:383 el0_sync+0x140/0x180 arch/arm64/kernel/entry.S:670 Freed by task 4269: stack_trace_save+0x80/0xb8 kernel/stacktrace.c:121 kasan_save_stack mm/kasan/common.c:48 [inline] kasan_set_track+0x38/0x6c mm/kasan/common.c:56 kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:355 __kasan_slab_free+0x124/0x150 mm/kasan/common.c:422 kasan_slab_free+0x10/0x1c mm/kasan/common.c:431 slab_free_hook mm/slub.c:1544 [inline] slab_free_freelist_hook mm/slub.c:1577 [inline] slab_free mm/slub.c:3142 [inline] kfree+0x104/0x38c mm/slub.c:4124 coalesced_mmio_destructor+0x94/0xa4 arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:102 kvm_iodevice_destructor include/kvm/iodev.h:61 [inline] kvm_io_bus_unregister_dev+0x248/0x280 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:4374 kvm_vm_ioctl_unregister_coalesced_mmio+0x158/0x1ec arch/arm64/kvm/../../../virt/kvm/coalesced_mmio.c:186 kvm_vm_ioctl+0xe30/0x14c4 arch/arm64/kvm/../../../virt/kvm/kvm_main.c:3755 vfs_ioctl fs/ioctl.c:48 [inline] __do_sys_ioctl fs/ioctl.c:753 [inline] __se_sys_ioctl fs/ioctl.c:739 [inline] __arm64_sys_ioctl+0xf88/0x131c fs/ioctl.c:739 __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline] invoke_syscall arch/arm64/kernel/sys ---truncated---

HighCVSS 7.8 · v3.1—No exploit Fix available

Memory safety

Published: May 21, 2024
Updated: Aug 5, 2026
EPSS: 0.2% · 17th percentile
CWE: CWE-416

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.2%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: 7.8
CNA · Linux: 7.8; agree

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel5.4.119 and later · before 5.4.134
linux linux kernel5.10.37 and later · before 5.10.52
linux linux kernel5.11.21 and later · before 5.12
linux linux kernel5.12.4 and later · before 5.12.19
linux linux kernel5.13 and later · before 5.13.4
linux linux kernel5.14

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 168e82f640ed1891a700bdb43e37da354b2ab63c, 5.13affected
- 7d1bc32d6477ff96a32695ea4be8144e4513ab2d and later · before f2ff9d03432fcb160e9f7d4be26174d89de2779aaffected · git
- 2a20592baff59c5351c5200ec667e1a2aa22af85 and later · before 679837dc0abaa2c6e2a7bcd86483e05eee1d5066affected · git
- 50cbad42bfea8c052b7ca590bd4126cdc898713c and later · before 8d7c539316d652d217e5e82b89ee204c812a7061affected · git
- 5d3c4c79384af06e3c8e25b7770b6247496b4417 and later · before 069d44a24c0ff8f85adf49233aae7a8ca16f5c7eaffected · git
- 5d3c4c79384af06e3c8e25b7770b6247496b4417 and later · before 23fa2e46a5556f787ce2ea1a315d3ab93cced204affected · git
- 5.4.119 and later · before 5.4.134affected · semver
- 5.10.37 and later · before 5.10.52affected · semver
- 5.12.4 and later · before 5.12.19affected · semver
- 5.11.21 and later · before 5.12affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 5.14.6-1	5.14.6-1
SUSE:Linux Enterprise High Availability Extension 12 SP5	kernel-default	before 4.12.14-122.228.1	4.12.14-122.228.1
SUSE:Linux Enterprise Live Patching 12 SP5	kgraft-patch-SLE12-SP5_Update_60	before 1-8.3.1	1-8.3.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-rt	before 4.12.14-10.200.1	4.12.14-10.200.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-rt_debug	before 4.12.14-10.200.1	4.12.14-10.200.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-source-rt	before 4.12.14-10.200.1	4.12.14-10.200.1
SUSE:Linux Enterprise Real Time 12 SP5	kernel-syms-rt	before 4.12.14-10.200.1	4.12.14-10.200.1
SUSE:Linux Enterprise Server 12 SP5	kernel-azure	before 4.12.14-16.197.1	4.12.14-16.197.1
SUSE:Linux Enterprise Server 12 SP5	kernel-source	before 4.12.14-122.228.1	4.12.14-122.228.1
SUSE:Linux Enterprise Server 12 SP5	kernel-source-azure	before 4.12.14-16.197.1	4.12.14-16.197.1
SUSE:Linux Enterprise Server 12 SP5	kernel-syms	before 4.12.14-122.228.1	4.12.14-122.228.1
SUSE:Linux Enterprise Server 12 SP5	kernel-syms-azure	before 4.12.14-16.197.1	4.12.14-16.197.1
SUSE:Linux Enterprise Software Development Kit 12 SP5	kernel-docs	before 4.12.14-122.228.2	4.12.14-122.228.2
SUSE:Linux Enterprise Software Development Kit 12 SP5	kernel-obs-build	before 4.12.14-122.228.2	4.12.14-122.228.2

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2021-47339May 21, 2024 · media: v4l2-core: explicitly clear ioctl input data
22Monitor
← EarlierCVE-2021-47340May 21, 2024 · jfs: fix GPF in diFree
22Monitor
Later →CVE-2021-47342May 21, 2024 · ext4: fix possible UAF when remounting r/o a mmp-protected file system
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	069d44a24c0ff8f85adf49233aae7a8ca16f5c7e	Vendor (CNA)
Linux Linux	23fa2e46a5556f787ce2ea1a315d3ab93cced204	Vendor (CNA)
Linux Linux	5.10.52	Vendor (CNA)
Linux Linux	5.12	Vendor (CNA)
Linux Linux	5.12.19	Vendor (CNA)
Linux Linux	5.4.134	Vendor (CNA)
Linux Linux	679837dc0abaa2c6e2a7bcd86483e05eee1d5066	Vendor (CNA)
Linux Linux	8d7c539316d652d217e5e82b89ee204c812a7061	Vendor (CNA)
Linux Linux	f2ff9d03432fcb160e9f7d4be26174d89de2779a	Vendor (CNA)
debian:linux	5.14.6-1 · Debian:12	Package registry (OSV)
suse:kernel-azure	4.12.14-16.197.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-default	4.12.14-122.228.1 · SUSE:Linux Enterprise High Availability Extension 12 SP5	Package registry (OSV)
suse:kernel-docs	4.12.14-122.228.2 · SUSE:Linux Enterprise Software Development Kit 12 SP5	Package registry (OSV)
suse:kernel-obs-build	4.12.14-122.228.2 · SUSE:Linux Enterprise Software Development Kit 12 SP5	Package registry (OSV)
suse:kernel-rt	4.12.14-10.200.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-rt_debug	4.12.14-10.200.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-source	4.12.14-122.228.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-source-azure	4.12.14-16.197.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-source-rt	4.12.14-10.200.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kernel-syms	4.12.14-122.228.1 · SUSE:Linux Enterprise Server 12 SP5	Package registry (OSV)
suse:kernel-syms-rt	4.12.14-10.200.1 · SUSE:Linux Enterprise Real Time 12 SP5	Package registry (OSV)
suse:kgraft-patch-SLE12-SP5_Update_60	1-8.3.1 · SUSE:Linux Enterprise Live Patching 12 SP5	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-24-0519 · May 22, 2024(Linux Kernel Güncellemesi)

All national notices →

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

Fix✗ → ✓Sep 28, 2026, 10:11 PM UTC

For records you follow, these changes also arrive as notifications. →

References

git.kernel.org/stable/c/069d44a24c0ff8f85adf49233aae7a8ca16f5c7e

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records