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NVD / CVE Program· CNA Linux

CVE-2021-47343: dm btree remove: assign new_root only when removal succeeds

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.27% (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 4c84b3e0728ffe10d89c633694c35a02b5c477dc, 73f27adaa73e3057a9ec464e33c4f54d34ea5de3, 89bf942314b78d454db92427201421b5dec132d9.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 5.5.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4c84b3e0728ffe10d89c633694c35a02b5c477dc, 73f27adaa73e3057a9ec464e33c4f54d34ea5de3, 89bf942314b78d454db92427201421b5dec132d9 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: dm btree remove: assign new_root only when removal succeeds remove_raw() in dm_btree_remove() may fail due to IO read error (e.g. read the content of origin block fails during shadowing), and the value of shadow_spine::root is uninitialized, but the uninitialized value is still assign to new_root in the end of dm_btree_remove(). For dm-thin, the value of pmd->details_root or pmd->root will become an uninitialized value, so if trying to read details_info tree again out-of-bound memory may occur as showed below: general protection fault, probably for non-canonical address 0x3fdcb14c8d7520 CPU: 4 PID: 515 Comm: dmsetup Not tainted 5.13.0-rc6 Hardware name: QEMU Standard PC RIP: 0010:metadata_ll_load_ie+0x14/0x30 Call Trace: sm_metadata_count_is_more_than_one+0xb9/0xe0 dm_tm_shadow_block+0x52/0x1c0 shadow_step+0x59/0xf0 remove_raw+0xb2/0x170 dm_btree_remove+0xf4/0x1c0 dm_pool_delete_thin_device+0xc3/0x140 pool_message+0x218/0x2b0 target_message+0x251/0x290 ctl_ioctl+0x1c4/0x4d0 dm_ctl_ioctl+0xe/0x20 __x64_sys_ioctl+0x7b/0xb0 do_syscall_64+0x40/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae Fixing it by only assign new_root when removal succeeds

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Aug 5, 2026
EPSS
0.2% · 19th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 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
5.5
CNA · Linux
7.8
2.3 point gap

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

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.

Follow CVE-2021-47343

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

VendorProduct
linuxlinux kernel

Affected versions

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

  • linux linux kernelbefore 4.4.276
  • linux linux kernel4.5 and later · before 4.9.276
  • linux linux kernel4.10 and later · before 4.14.240
  • linux linux kernel4.15 and later · before 4.19.198
  • linux linux kernel4.20 and later · before 5.4.133
  • linux linux kernel5.5 and later · before 5.10.51
  • linux linux kernel5.11 and later · before 5.12.18
  • linux linux kernel5.13 and later · before 5.13.3

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

    • 3.2affected
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 4c84b3e0728ffe10d89c633694c35a02b5c477dcaffected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before c154775619186781aaf8a99333ac07437a1768d5affected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 73f27adaa73e3057a9ec464e33c4f54d34ea5de3affected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 8fbae4a1bdb5b889490cdee929e68540151536e5affected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 964d57d1962d7e68f0f578f05d9ae4a104d74851affected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before ba47e65a5de3e0e8270301a409fc63d3129fdb9eaffected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before 89bf942314b78d454db92427201421b5dec132d9affected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before ad365e9351ac2b450e7e79932ff6abf59342d91aaffected · git
    • 3241b1d3e0aaafbfcd320f4d71ade629728cc4f4 and later · before b6e58b5466b2959f83034bead2e2e1395cca8aebaffected · git

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.14.6-15.14.6-1

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-2021-47341May 21, 2024 · KVM: mmio: Fix use-after-free Read in kvm_vm_ioctl_unregister_coalesced_mmio
    31Monitor
  • ← EarlierCVE-2021-47342May 21, 2024 · ext4: fix possible UAF when remounting r/o a mmp-protected file system
    31Monitor
  • Later →CVE-2021-47344May 21, 2024 · media: zr364xx: fix memory leak in zr364xx_start_readpipe
    22Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
Linux Linux4c84b3e0728ffe10d89c633694c35a02b5c477dcVendor (CNA)
Linux Linux73f27adaa73e3057a9ec464e33c4f54d34ea5de3Vendor (CNA)
Linux Linux89bf942314b78d454db92427201421b5dec132d9Vendor (CNA)
Linux Linux8fbae4a1bdb5b889490cdee929e68540151536e5Vendor (CNA)
Linux Linux964d57d1962d7e68f0f578f05d9ae4a104d74851Vendor (CNA)
Linux Linuxad365e9351ac2b450e7e79932ff6abf59342d91aVendor (CNA)
Linux Linuxb6e58b5466b2959f83034bead2e2e1395cca8aebVendor (CNA)
Linux Linuxba47e65a5de3e0e8270301a409fc63d3129fdb9eVendor (CNA)
Linux Linuxc154775619186781aaf8a99333ac07437a1768d5Vendor (CNA)
debian:linux5.14.6-1 · Debian:12Package 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.

  • CVE-2022-2196498 days apartSpeculative execution attacks in KVM VMX
    35Monitor
  • CVE-2022-49099281 days apartDrivers: hv: vmbus: Fix initialization of device object in vmbus_device_register()
    22Monitor
  • CVE-2025-38523452 days apartcifs: Fix the smbd_response slab to allow usercopy
    22Monitor

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.

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
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-1188 · Initialization of a Resource with an Insecure Default

CVSS vector

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

nvd-primary

Attack context

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

Change log

  1. Fix✗ → ✓

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

References

Show all references (8 more)

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

All records