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NVD / CVE Program· CNA Linux

CVE-2021-47060: KVM: Stop looking for coalesced MMIO zones if the bus is destroyed

HighCVSS 7.8 · v3.1—No exploit Fix available

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: 0.24% (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 168e82f640ed1891a700bdb43e37da354b2ab63c, 2a20592baff59c5351c5200ec667e1a2aa22af85, 4.10.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 168e82f640ed1891a700bdb43e37da354b2ab63c, 2a20592baff59c5351c5200ec667e1a2aa22af85, 4.10 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: Stop looking for coalesced MMIO zones if the bus is destroyed Abort the walk of coalesced MMIO zones if kvm_io_bus_unregister_dev() fails to allocate memory for the new instance of the bus. If it can't instantiate a new bus, unregister_dev() destroys all devices _except_ the target device. But, it doesn't tell the caller that it obliterated the bus and invoked the destructor for all devices that were on the bus. In the coalesced MMIO case, this can result in a deleted list entry dereference due to attempting to continue iterating on coalesced_zones after future entries (in the walk) have been deleted. Opportunistically add curly braces to the for-loop, which encompasses many lines but sneaks by without braces due to the guts being a single if statement.

Published
Feb 29, 2024
Updated
Aug 5, 2026
EPSS
0.2% · 15th percentile
CWE
—

Report tools

JSON

Action score

31

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
—
CNA · Linux
7.8
NVD has not scored this yet; the score shown is the CNA’s.

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

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

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Follow CVE-2021-47060

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  • when exploit code appears or is weaponized
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  • 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

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

    • f0dfffce3f4ffd5f822568a4a6fb34c010e939d1, 840e124f89a5127e7eb97ebf377f4b8ca745c070, 40a023f681befd9b2862a3c16fb306a38b359ae5, 19184bd06f488af62924ff1747614a8cb284ad63, 68c125324b5e1d1d22805653735442923d896a1d, 5.9affected
    • 41b2ea7a6a11e2b1a7f2c29e1675a709a6b2b98d and later · before 7d1bc32d6477ff96a32695ea4be8144e4513ab2daffected · git
    • f65886606c2d3b562716de030706dfe1bea4ed5e and later · before 2a20592baff59c5351c5200ec667e1a2aa22af85affected · git
    • f65886606c2d3b562716de030706dfe1bea4ed5e and later · before 168e82f640ed1891a700bdb43e37da354b2ab63caffected · git
    • f65886606c2d3b562716de030706dfe1bea4ed5e and later · before 50cbad42bfea8c052b7ca590bd4126cdc898713caffected · git
    • f65886606c2d3b562716de030706dfe1bea4ed5e and later · before 5d3c4c79384af06e3c8e25b7770b6247496b4417affected · git
    • 5.4.66 and later · before 5.4.119affected · semver
    • 4.4.238 and later · before 4.5affected · semver
    • 4.9.238 and later · before 4.10affected · semver
    • 4.14.200 and later · before 4.15affected · semver
Affected versions · NVD (4)

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

  • linux linux kernel5.4.66 and later · before 5.4.119
  • linux linux kernel5.9 and later · before 5.10.37
  • linux linux kernel5.11 and later · before 5.11.21
  • linux linux kernel5.12 and later · before 5.12.4

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.10.38-15.10.38-1

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-2021-47058Feb 29, 2024 · regmap: set debugfs_name to NULL after it is freed
    31Monitor
  • ← EarlierCVE-2021-47059Feb 29, 2024 · crypto: sun8i-ss - fix result memory leak on error path
    22Monitor
  • Later →CVE-2021-47061Feb 29, 2024 · KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU
    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 / packageFixed versionSource
Linux Linux168e82f640ed1891a700bdb43e37da354b2ab63cVendor (CNA)
Linux Linux2a20592baff59c5351c5200ec667e1a2aa22af85Vendor (CNA)
Linux Linux4.10Vendor (CNA)
Linux Linux4.15Vendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux4.5Vendor (CNA)
Linux Linux5.4.119Vendor (CNA)
Linux Linux5.9Vendor (CNA)
Linux Linux50cbad42bfea8c052b7ca590bd4126cdc898713cVendor (CNA)
Linux Linux5d3c4c79384af06e3c8e25b7770b6247496b4417Vendor (CNA)
Linux Linux7d1bc32d6477ff96a32695ea4be8144e4513ab2dVendor (CNA)
debian:linux5.10.38-1 · 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.

National notice (Türkiye Cybersecurity Directorate / USOM)

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

All national notices →

Not on record for this CVE: EPSS history · patch commit or PR link · researcher credit · variant or chain candidate · public bounty program.

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)

—

CVSS vector

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

nvd-secondary

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.

References

Show all references (4 more)

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

All records