Skip to content
Noroxi
NVD / CVE Program· CNA Linux

CVE-2021-47068: net/nfc: fix use-after-free llcp_sock_bind/connect

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: 0.23% (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 18175fe17ae043a0b81e5d511f8817825784c299, 18ae4a192a4496e48a5490b52812645d2413307c, 26157c82ba756767b2bd66d28a71b1bc454447f6.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 18175fe17ae043a0b81e5d511f8817825784c299, 18ae4a192a4496e48a5490b52812645d2413307c, 26157c82ba756767b2bd66d28a71b1bc454447f6 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/nfc: fix use-after-free llcp_sock_bind/connect Commits 8a4cd82d ("nfc: fix refcount leak in llcp_sock_connect()") and c33b1cc62 ("nfc: fix refcount leak in llcp_sock_bind()") fixed a refcount leak bug in bind/connect but introduced a use-after-free if the same local is assigned to 2 different sockets. This can be triggered by the following simple program: int sock1 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); int sock2 = socket( AF_NFC, SOCK_STREAM, NFC_SOCKPROTO_LLCP ); memset( &addr, 0, sizeof(struct sockaddr_nfc_llcp) ); addr.sa_family = AF_NFC; addr.nfc_protocol = NFC_PROTO_NFC_DEP; bind( sock1, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) bind( sock2, (struct sockaddr*) &addr, sizeof(struct sockaddr_nfc_llcp) ) close(sock1); close(sock2); Fix this by assigning NULL to llcp_sock->local after calling nfc_llcp_local_put. This addresses CVE-2021-23134.

Published
Feb 29, 2024
Updated
Aug 5, 2026
EPSS
0.2% · 14th percentile

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
total

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.

Follow CVE-2021-47068

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

One daily email digest (06:00 UTC); connect a webhook for KEV listings and weaponized exploits every 10 minutes on paid plans, on the hour on the free plan.

Your free account also gets you

  • Stack alerts: add the products and versions you run, get the new CVEs that affect them
  • Uptime monitoring: 1 site, instant email when it goes down
  • Add your domain: subdomains and takeover risk scanned every week (1 domain)
  • 10 scans an hour on the security tools, at most 30 a day (3 a day without an account), an API key and MCP
  • All your scans in one panel: findings, what changed in the last scan, a report per domain or per client (PDF, share link)
All free tools

Sign up with email · Have an account? Sign in

Free account, no card. Unfollow any time.

Don't want an account? Get "Exploited this week" by email every MondayDon't want an account? RSS feed for linux records
Is your version affected? Check it

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.

We use this product, ask for help

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 kernel4.4.267 and later · before 4.4.269
  • linux linux kernel4.9.267 and later · before 4.9.269
  • linux linux kernel4.14.231 and later · before 4.14.233
  • linux linux kernel4.19.187 and later · before 4.19.191
  • linux linux kernel5.4.112 and later · before 5.4.119
  • linux linux kernel5.10.30 and later · before 5.10.37
  • linux linux kernel5.11.14 and later · before 5.11.21
  • linux linux kernel5.12 and later · before 5.12.4

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

    • 5.12affected
    • a1cdd18c49d23ec38097ac2c5b0d761146fc0109 and later · before 26157c82ba756767b2bd66d28a71b1bc454447f6affected · git
    • 18013007b596771bf5f5e7feee9586fb0386ad14 and later · before ccddad6dd28530e716448e594c9ca7c76ccd0570affected · git
    • 538a6ff11516d38a61e237d2d2dc04c30c845fbe and later · before 18ae4a192a4496e48a5490b52812645d2413307caffected · git
    • adbb1d218c5f56dbae052765da83c0f57fce2a31 and later · before 48fba458fe54cc2a980a05c13e6c19b8b2cfb610affected · git
    • c89903c9eff219a4695e63715cf922748d743f65 and later · before e32352070bcac22be6ed8ab635debc280bb65b8caffected · git
    • 6fb003e5ae18d8cda4c8a1175d9dd8db12bec049 and later · before 6b7021ed36dabf29e56842e3408781cd3b82ef6eaffected · git
    • 8c9e4971e142e2899606a2490b77a1208c1f4638 and later · before 374cdde4dcc9c909a60713abdbbf96d5e3e09f91affected · git
    • c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d and later · before 18175fe17ae043a0b81e5d511f8817825784c299affected · git
    • c33b1cc62ac05c1dbb1cdafe2eb66da01c76ca8d and later · before c61760e6940dd4039a7f5e84a6afc9cdbf4d82b6affected · git

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-2021-47066Feb 29, 2024 · async_xor: increase src_offs when dropping destination page
    22Monitor
  • ← EarlierCVE-2021-47067Feb 29, 2024 · soc/tegra: regulators: Fix locking up when voltage-spread is out of range
    22Monitor
  • Later →CVE-2023-52497Mar 1, 2024 · erofs: fix lz4 inplace decompression
    24Monitor

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 Linux18175fe17ae043a0b81e5d511f8817825784c299Vendor (CNA)
Linux Linux18ae4a192a4496e48a5490b52812645d2413307cVendor (CNA)
Linux Linux26157c82ba756767b2bd66d28a71b1bc454447f6Vendor (CNA)
Linux Linux374cdde4dcc9c909a60713abdbbf96d5e3e09f91Vendor (CNA)
Linux Linux4.14.233Vendor (CNA)
Linux Linux4.19.191Vendor (CNA)
Linux Linux4.4.269Vendor (CNA)
Linux Linux4.9.269Vendor (CNA)
Linux Linux48fba458fe54cc2a980a05c13e6c19b8b2cfb610Vendor (CNA)
Linux Linux5.10.37Vendor (CNA)
Linux Linux5.11.21Vendor (CNA)
Linux Linux5.4.119Vendor (CNA)
Linux Linux6b7021ed36dabf29e56842e3408781cd3b82ef6eVendor (CNA)
Linux Linuxc61760e6940dd4039a7f5e84a6afc9cdbf4d82b6Vendor (CNA)
Linux Linuxccddad6dd28530e716448e594c9ca7c76ccd0570Vendor (CNA)
Linux Linuxe32352070bcac22be6ed8ab635debc280bb65b8cVendor (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.

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
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

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

Fixed

c
lock(&dev->lock);free(dev->buf);dev->buf = NULL;unlock(&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

  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