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NVD / CVE Program· CNA Linux

CVE-2021-47237: net: hamradio: fix memory leak in mkiss_close

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: 0.22% (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 290b0b6432e2599021db0b8d6046f756d931c29f, 3942d0f9ace1a95a74930b5b4fc0e5005c62b37b, 765a8a04f828db7222b36a42b1031f576bfe95c3.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 290b0b6432e2599021db0b8d6046f756d931c29f, 3942d0f9ace1a95a74930b5b4fc0e5005c62b37b, 765a8a04f828db7222b36a42b1031f576bfe95c3 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: net: hamradio: fix memory leak in mkiss_close My local syzbot instance hit memory leak in mkiss_open()[1]. The problem was in missing free_netdev() in mkiss_close(). In mkiss_open() netdevice is allocated and then registered, but in mkiss_close() netdevice was only unregistered, but not freed. Fail log: BUG: memory leak unreferenced object 0xffff8880281ba000 (size 4096): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): 61 78 30 00 00 00 00 00 00 00 00 00 00 00 00 00 ax0............. 00 27 fa 2a 80 88 ff ff 00 00 00 00 00 00 00 00 .'.*............ backtrace: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706e7e8>] alloc_netdev_mqs+0x98/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff8880141a9a00 (size 96): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): e8 a2 1b 28 80 88 ff ff e8 a2 1b 28 80 88 ff ff ...(.......(.... 98 92 9c aa b0 40 02 00 00 00 00 00 00 00 00 00 .....@.......... backtrace: [<ffffffff8709f68b>] __hw_addr_create_ex+0x5b/0x310 [<ffffffff8709fb38>] __hw_addr_add_ex+0x1f8/0x2b0 [<ffffffff870a0c7b>] dev_addr_init+0x10b/0x1f0 [<ffffffff8706e88b>] alloc_netdev_mqs+0x13b/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff8880219bfc00 (size 512): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): 00 a0 1b 28 80 88 ff ff 80 8f b1 8d ff ff ff ff ...(............ 80 8f b1 8d ff ff ff ff 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706eec7>] alloc_netdev_mqs+0x777/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae BUG: memory leak unreferenced object 0xffff888029b2b200 (size 256): comm "syz-executor.1", pid 11443, jiffies 4295046091 (age 17.660s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff81a27201>] kvmalloc_node+0x61/0xf0 [<ffffffff8706f062>] alloc_netdev_mqs+0x912/0xe80 [<ffffffff84e64192>] mkiss_open+0xb2/0x6f0 [1] [<ffffffff842355db>] tty_ldisc_open+0x9b/0x110 [<ffffffff84236488>] tty_set_ldisc+0x2e8/0x670 [<ffffffff8421f7f3>] tty_ioctl+0xda3/0x1440 [<ffffffff81c9f273>] __x64_sys_ioctl+0x193/0x200 [<ffffffff8911263a>] do_syscall_64+0x3a/0xb0 [<ffffffff89200068>] entry_SYSCALL_64_after_hwframe+0x44/0xae

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 13th 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.

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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When you'll hear from us

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  • 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 kernel2.6.14 and later · before 4.4.274
  • linux linux kernel4.5 and later · before 4.9.274
  • linux linux kernel4.10 and later · before 4.14.238
  • linux linux kernel4.15 and later · before 4.19.196
  • linux linux kernel4.20 and later · before 5.4.128
  • linux linux kernel5.5 and later · before 5.10.46
  • linux linux kernel5.11 and later · before 5.12.13
  • linux linux kernel5.13

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

    • 2.6.14affected
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before c634ba0b4159838ff45a60d3a0ace3b4118077a5affected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before 3942d0f9ace1a95a74930b5b4fc0e5005c62b37baffected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before 765a8a04f828db7222b36a42b1031f576bfe95c3affected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before c16c4716a1b5ba4f83c7e00da457cba06761f119affected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before a49cbb762ef20655f5c91abdc13658b0af5e159daffected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before 290b0b6432e2599021db0b8d6046f756d931c29faffected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before f4de2b43d13b7cf3ced9310e371b90c836dbd7cdaffected · git
    • 815f62bf742718458ba822a7e1f51f285eb997f2 and later · before 7edcc682301492380fbdd604b4516af5ae667a13affected · git
    • before 2.6.14not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 5.10.46-15.10.46-1
SUSE:Linux Enterprise High Availability Extension 12 SP5kernel-defaultbefore 4.12.14-122.219.14.12.14-122.219.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-64kbbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-default-basebefore 5.3.18-150300.59.164.1.150300.18.96.15.3.18-150300.59.164.1.150300.18.96.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-docsbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-obs-buildbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-preemptbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-sourcebefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-symsbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise Live Patching 12 SP5kgraft-patch-SLE12-SP5_Update_57before 1-8.3.11-8.3.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-defaultbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-livepatch-SLE15-SP3_Update_45before 1-150300.7.3.11-150300.7.3.1
SUSE:Linux Enterprise Micro 5.1kernel-rtbefore 5.3.18-150300.172.15.3.18-150300.172.1
SUSE:Linux Enterprise Micro 5.1kernel-source-rtbefore 5.3.18-150300.172.15.3.18-150300.172.1
SUSE:Linux Enterprise Real Time 12 SP5kernel-rtbefore 4.12.14-10.188.14.12.14-10.188.1
SUSE:Linux Enterprise Real Time 12 SP5kernel-rt_debugbefore 4.12.14-10.188.14.12.14-10.188.1
SUSE:Linux Enterprise Real Time 12 SP5kernel-source-rtbefore 4.12.14-10.188.14.12.14-10.188.1
SUSE:Linux Enterprise Real Time 12 SP5kernel-syms-rtbefore 4.12.14-10.188.14.12.14-10.188.1
SUSE:Linux Enterprise Server 12 SP5kernel-azurebefore 4.12.14-16.188.14.12.14-16.188.1
SUSE:Linux Enterprise Server 12 SP5kernel-sourcebefore 4.12.14-122.219.14.12.14-122.219.1
SUSE:Linux Enterprise Server 12 SP5kernel-source-azurebefore 4.12.14-16.188.14.12.14-16.188.1
SUSE:Linux Enterprise Server 12 SP5kernel-symsbefore 4.12.14-122.219.14.12.14-122.219.1
SUSE:Linux Enterprise Server 12 SP5kernel-syms-azurebefore 4.12.14-16.188.14.12.14-16.188.1
SUSE:Linux Enterprise Server 15 SP3-LTSSkernel-zfcpdumpbefore 5.3.18-150300.59.164.15.3.18-150300.59.164.1

+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-2021-47235May 21, 2024 · net: ethernet: fix potential use-after-free in ec_bhf_remove
    31Monitor
  • ← EarlierCVE-2021-47236May 21, 2024 · net: cdc_eem: fix tx fixup skb leak
    22Monitor
  • Later →CVE-2021-47238May 21, 2024 · net: ipv4: fix memory leak in ip_mc_add1_src
    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 Linux290b0b6432e2599021db0b8d6046f756d931c29fVendor (CNA)
Linux Linux3942d0f9ace1a95a74930b5b4fc0e5005c62b37bVendor (CNA)
Linux Linux765a8a04f828db7222b36a42b1031f576bfe95c3Vendor (CNA)
Linux Linux7edcc682301492380fbdd604b4516af5ae667a13Vendor (CNA)
Linux Linuxa49cbb762ef20655f5c91abdc13658b0af5e159dVendor (CNA)
Linux Linuxc16c4716a1b5ba4f83c7e00da457cba06761f119Vendor (CNA)
Linux Linuxc634ba0b4159838ff45a60d3a0ace3b4118077a5Vendor (CNA)
Linux Linuxf4de2b43d13b7cf3ced9310e371b90c836dbd7cdVendor (CNA)
debian:linux5.10.46-1 · Debian:12Package registry (OSV)
suse:kernel-azure4.12.14-16.188.1 · SUSE:Linux Enterprise Server 12 SP5Package registry (OSV)
suse:kernel-default4.12.14-122.219.1 · SUSE:Linux Enterprise High Availability Extension 12 SP5Package registry (OSV)
suse:kernel-docs4.12.14-122.219.1 · SUSE:Linux Enterprise Software Development Kit 12 SP5Package registry (OSV)
suse:kernel-obs-build4.12.14-122.219.1 · SUSE:Linux Enterprise Software Development Kit 12 SP5Package registry (OSV)
suse:kernel-rt4.12.14-10.188.1 · SUSE:Linux Enterprise Real Time 12 SP5Package registry (OSV)
suse:kernel-rt_debug4.12.14-10.188.1 · SUSE:Linux Enterprise Real Time 12 SP5Package registry (OSV)
suse:kernel-source4.12.14-122.219.1 · SUSE:Linux Enterprise Server 12 SP5Package registry (OSV)
suse:kernel-source-azure4.12.14-16.188.1 · SUSE:Linux Enterprise Server 12 SP5Package registry (OSV)
suse:kernel-source-rt4.12.14-10.188.1 · SUSE:Linux Enterprise Real Time 12 SP5Package registry (OSV)
suse:kernel-syms-azure4.12.14-16.188.1 · SUSE:Linux Enterprise Server 12 SP5Package registry (OSV)
suse:kernel-syms-rt4.12.14-10.188.1 · SUSE:Linux Enterprise Real Time 12 SP5Package registry (OSV)
suse:kgraft-patch-SLE12-SP5_Update_571-8.3.1 · SUSE:Linux Enterprise Live Patching 12 SP5Package 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.

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-401 · Missing Release of Memory after Effective Lifetime

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.

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

Change log

  1. Fix✗ → ✓

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

References

Show all references (7 more)

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

All records