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NVD / CVE Program· CNA Linux

CVE-2023-52843: llc: verify mac len before reading mac header

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: 0.24% (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 0a720d0259ad3521ec6c9e4199f9f6fc75bac77a, 352887b3edd007cf9b0abc30fe9d98622acd859b, 3a2653828ffc6101aef80bf58d5b77484239f779.

Low priority for now. Upgrade to Linux Linux 0a720d0259ad3521ec6c9e4199f9f6fc75bac77a, 352887b3edd007cf9b0abc30fe9d98622acd859b, 3a2653828ffc6101aef80bf58d5b77484239f779 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: llc: verify mac len before reading mac header LLC reads the mac header with eth_hdr without verifying that the skb has an Ethernet header. Syzbot was able to enter llc_rcv on a tun device. Tun can insert packets without mac len and with user configurable skb->protocol (passing a tun_pi header when not configuring IFF_NO_PI). BUG: KMSAN: uninit-value in llc_station_ac_send_test_r net/llc/llc_station.c:81 [inline] BUG: KMSAN: uninit-value in llc_station_rcv+0x6fb/0x1290 net/llc/llc_station.c:111 llc_station_ac_send_test_r net/llc/llc_station.c:81 [inline] llc_station_rcv+0x6fb/0x1290 net/llc/llc_station.c:111 llc_rcv+0xc5d/0x14a0 net/llc/llc_input.c:218 __netif_receive_skb_one_core net/core/dev.c:5523 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5637 netif_receive_skb_internal net/core/dev.c:5723 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5782 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555 tun_get_user+0x54c5/0x69c0 drivers/net/tun.c:2002 Add a mac_len test before all three eth_hdr(skb) calls under net/llc. There are further uses in include/net/llc_pdu.h. All these are protected by a test skb->protocol == ETH_P_802_2. Which does not protect against this tun scenario. But the mac_len test added in this patch in llc_fixup_skb will indirectly protect those too. That is called from llc_rcv before any other LLC code. It is tempting to just add a blanket mac_len check in llc_rcv, but not sure whether that could break valid LLC paths that do not assume an Ethernet header. 802.2 LLC may be used on top of non-802.3 protocols in principle. The below referenced commit shows that used to, on top of Token Ring. At least one of the three eth_hdr uses goes back to before the start of git history. But the one that syzbot exercises is introduced in this commit. That commit is old enough (2008), that effectively all stable kernels should receive this.

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
May 21, 2024
Updated
Jun 17, 2026
EPSS
0.2% · 15th 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.

Follow CVE-2023-52843

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 kernel2.6.26 and later · before 4.14.330
  • linux linux kernel4.15 and later · before 4.19.299
  • linux linux kernel4.20 and later · before 5.4.261
  • linux linux kernel5.5 and later · before 5.10.201
  • linux linux kernel5.11 and later · before 5.15.139
  • linux linux kernel5.16 and later · before 6.1.63
  • linux linux kernel6.2 and later · before 6.5.12
  • linux linux kernel6.6 and later · before 6.6.2
  • linux linux kernel2.6.25

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

    • 2.6.25affected
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 900a4418e3f66a32db6baaf23f92b99c20ae6535affected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 9a3f9054a5227d7567cba1fb821df48ccecad10caffected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before cbdcdf42d15dac74c7287679fb2a9d955f8feb1faffected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 3a2653828ffc6101aef80bf58d5b77484239f779affected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 352887b3edd007cf9b0abc30fe9d98622acd859baffected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before f980e9a57dfb9530f1f4ee41a2420f2a256d7b29affected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 0a720d0259ad3521ec6c9e4199f9f6fc75bac77aaffected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before ff5cb6a4f0c6d7fbdc84858323fb4b7af32cfd79affected · git
    • f83f1768f833cb45bc93429fdc552252a4f55ac3 and later · before 7b3ba18703a63f6fd487183b9262b08e5632da1baffected · git

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.64-16.1.64-1
Debian:13linuxbefore 6.6.8-16.6.8-1

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-2023-52841May 21, 2024 · media: vidtv: mux: Add check and kfree for kstrdup
    22Monitor
  • ← EarlierCVE-2023-52842May 21, 2024 · virtio/vsock: Fix uninit-value in virtio_transport_recv_pkt()
    28Monitor
  • Later →CVE-2023-52844May 21, 2024 · media: vidtv: psi: Add check for kstrdup
    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 Linux0a720d0259ad3521ec6c9e4199f9f6fc75bac77aVendor (CNA)
Linux Linux352887b3edd007cf9b0abc30fe9d98622acd859bVendor (CNA)
Linux Linux3a2653828ffc6101aef80bf58d5b77484239f779Vendor (CNA)
Linux Linux7b3ba18703a63f6fd487183b9262b08e5632da1bVendor (CNA)
Linux Linux900a4418e3f66a32db6baaf23f92b99c20ae6535Vendor (CNA)
Linux Linux9a3f9054a5227d7567cba1fb821df48ccecad10cVendor (CNA)
Linux Linuxcbdcdf42d15dac74c7287679fb2a9d955f8feb1fVendor (CNA)
Linux Linuxf980e9a57dfb9530f1f4ee41a2420f2a256d7b29Vendor (CNA)
Linux Linuxff5cb6a4f0c6d7fbdc84858323fb4b7af32cfd79Vendor (CNA)
debian:linux6.1.64-1 · 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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-2024-50302182 days apartHID: core: zero-initialize the report bufferKEV
    52Plan
  • CVE-2024-47685153 days apartnetfilter: nf_reject_ipv6: fix nf_reject_ip6_tcphdr_put()
    36Monitor
  • CVE-2021-475533 days apartsched/scs: Reset task stack state in bringup_cpu()
    31Monitor
  • CVE-2024-368989 days apartgpiolib: cdev: fix uninitialised kfifo
    31Monitor
  • CVE-2024-2702220 days apartfork: defer linking file vma until vma is fully initialized
    31Monitor
  • CVE-2024-50143170 days apartudf: fix uninit-value use in udf_get_fileshortad
    31Monitor

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).

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-908 · Use of Uninitialized Resource

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 (8 more)

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

All records