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NVD / CVE Program· CNA Linux

CVE-2021-47248: udp: fix race between close() and udp_abort()

Noroxi assessment

Priority: Monitor (action score 18/100)

  • 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: 0.19% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: Linux Linux 2f73448041bd0682d4b552cfd314ace66107f1ad, 5a88477c1c85e4baa51e91f2d40f2166235daa56, 65310b0aff86980a011c7c7bfa487a333d4ca241.
  • Severity is disputed: the assigning authority (CNA) scores it 7.8, NVD 4.7.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 2f73448041bd0682d4b552cfd314ace66107f1ad, 5a88477c1c85e4baa51e91f2d40f2166235daa56, 65310b0aff86980a011c7c7bfa487a333d4ca241 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: udp: fix race between close() and udp_abort() Kaustubh reported and diagnosed a panic in udp_lib_lookup(). The root cause is udp_abort() racing with close(). Both racing functions acquire the socket lock, but udp{v6}_destroy_sock() release it before performing destructive actions. We can't easily extend the socket lock scope to avoid the race, instead use the SOCK_DEAD flag to prevent udp_abort from doing any action when the critical race happens. Diagnosed-and-tested-by: Kaustubh Pandey <kapandey@codeaurora.org>

MediumCVSS 4.7 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Aug 5, 2026
EPSS
0.1% · 8th percentile

Report tools

JSON

Action score

18

Monitor

Low priority for now.

CVSS
18 / 40 · 4.7 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
4.7
CNA · Linux
7.8
3.1 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-2021-47248

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 kernel4.9 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

    • 4.9affected
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before e3c36c773aed0fef8b1d3d555b43393ec564400faffected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before a0882f68f54f7a8b6308261acee9bd4faab5a69eaffected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before 2f73448041bd0682d4b552cfd314ace66107f1adaffected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before 5a88477c1c85e4baa51e91f2d40f2166235daa56affected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before 8729ec8a2238152a4afc212a331a6cd2c61aeeacaffected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before 65310b0aff86980a011c7c7bfa487a333d4ca241affected · git
    • 5d77dca82839ef016a93ad7acd7058b14d967752 and later · before a8b897c7bcd47f4147d066e22cc01d1026d7640eaffected · git
    • before 4.9not affected · semver
    • 4.9.274 and later · up to and including 4.9.*not 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 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-default-basebefore 5.3.18-150300.59.201.1.150300.18.120.15.3.18-150300.59.201.1.150300.18.120.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-docsbefore 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-obs-buildbefore 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-preemptbefore 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-sourcebefore 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSSkernel-symsbefore 5.3.18-150300.59.201.15.3.18-150300.59.201.1
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 5.3.18-150300.59.201.15.3.18-150300.59.201.1
SUSE:Linux Enterprise Live Patching 15 SP3kernel-livepatch-SLE15-SP3_Update_56before 1-150300.7.3.11-150300.7.3.1
SUSE:Linux Enterprise Micro 5.1kernel-rtbefore 5.3.18-150300.205.15.3.18-150300.205.1
SUSE:Linux Enterprise Micro 5.1kernel-source-rtbefore 5.3.18-150300.205.15.3.18-150300.205.1
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 5.3.18-150300.59.201.15.3.18-150300.59.201.1

+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-2021-47246May 21, 2024 · net/mlx5e: Fix page reclaim for dead peer hairpin
    22Monitor
  • ← EarlierCVE-2021-47247May 21, 2024 · net/mlx5e: Fix use-after-free of encap entry in neigh update handler
    31Monitor
  • Later →CVE-2021-47249May 21, 2024 · net: rds: fix memory leak in rds_recvmsg
    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 Linux2f73448041bd0682d4b552cfd314ace66107f1adVendor (CNA)
Linux Linux5a88477c1c85e4baa51e91f2d40f2166235daa56Vendor (CNA)
Linux Linux65310b0aff86980a011c7c7bfa487a333d4ca241Vendor (CNA)
Linux Linux8729ec8a2238152a4afc212a331a6cd2c61aeeacVendor (CNA)
Linux Linuxa0882f68f54f7a8b6308261acee9bd4faab5a69eVendor (CNA)
Linux Linuxa8b897c7bcd47f4147d066e22cc01d1026d7640eVendor (CNA)
Linux Linuxe3c36c773aed0fef8b1d3d555b43393ec564400fVendor (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.
  • Special conditions such as timing or configuration are required.

If successful

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

Weakness class (CWE)

CWE-362 · Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

CVSS vector

CVSS:3.1/AV:L/AC:H/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.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

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

References

Show all references (6 more)

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

All records