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NVD / CVE Program· CNA Linux

CVE-2023-53667: net: cdc_ncm: Deal with too low values of dwNtbOutMaxSize

MediumCVSS 5.5 · v3.1—No exploit Fix available

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: 0.14% (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 2334ff0b343ba6ba7a6c0586fcc83992bbbc1776, 42b78c8cc774b47023d6d16d96d54cc7015e4a07, 6147745d43ff4e0d2c542e5b93e398ef0ee4db00.

Low priority for now. Upgrade to Linux Linux 2334ff0b343ba6ba7a6c0586fcc83992bbbc1776, 42b78c8cc774b47023d6d16d96d54cc7015e4a07, 6147745d43ff4e0d2c542e5b93e398ef0ee4db00 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: cdc_ncm: Deal with too low values of dwNtbOutMaxSize Currently in cdc_ncm_check_tx_max(), if dwNtbOutMaxSize is lower than the calculated "min" value, but greater than zero, the logic sets tx_max to dwNtbOutMaxSize. This is then used to allocate a new SKB in cdc_ncm_fill_tx_frame() where all the data is handled. For small values of dwNtbOutMaxSize the memory allocated during alloc_skb(dwNtbOutMaxSize, GFP_ATOMIC) will have the same size, due to how size is aligned at alloc time: size = SKB_DATA_ALIGN(size); size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info)); Thus we hit the same bug that we tried to squash with commit 2be6d4d16a084 ("net: cdc_ncm: Allow for dwNtbOutMaxSize to be unset or zero") Low values of dwNtbOutMaxSize do not cause an issue presently because at alloc_skb() time more memory (512b) is allocated than required for the SKB headers alone (320b), leaving some space (512b - 320b = 192b) for CDC data (172b). However, if more elements (for example 3 x u64 = [24b]) were added to one of the SKB header structs, say 'struct skb_shared_info', increasing its original size (320b [320b aligned]) to something larger (344b [384b aligned]), then suddenly the CDC data (172b) no longer fits in the spare SKB data area (512b - 384b = 128b). Consequently the SKB bounds checking semantics fails and panics: skbuff: skb_over_panic: text:ffffffff831f755b len:184 put:172 head:ffff88811f1c6c00 data:ffff88811f1c6c00 tail:0xb8 end:0x80 dev:<NULL> ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:113! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 0 PID: 57 Comm: kworker/0:2 Not tainted 5.15.106-syzkaller-00249-g19c0ed55a470 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023 Workqueue: mld mld_ifc_work RIP: 0010:skb_panic net/core/skbuff.c:113 [inline] RIP: 0010:skb_over_panic+0x14c/0x150 net/core/skbuff.c:118 [snip] Call Trace: <TASK> skb_put+0x151/0x210 net/core/skbuff.c:2047 skb_put_zero include/linux/skbuff.h:2422 [inline] cdc_ncm_ndp16 drivers/net/usb/cdc_ncm.c:1131 [inline] cdc_ncm_fill_tx_frame+0x11ab/0x3da0 drivers/net/usb/cdc_ncm.c:1308 cdc_ncm_tx_fixup+0xa3/0x100 Deal with too low values of dwNtbOutMaxSize, clamp it in the range [USB_CDC_NCM_NTB_MIN_OUT_SIZE, CDC_NCM_NTB_MAX_SIZE_TX]. We ensure enough data space is allocated to handle CDC data by making sure dwNtbOutMaxSize is not smaller than USB_CDC_NCM_NTB_MIN_OUT_SIZE.

Published
Oct 7, 2025
Updated
Nov 5, 2026
EPSS
0.1% · 4th 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 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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  • No public exploit code on record
  • A fix has been released

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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

    • 3.16affected
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 2334ff0b343ba6ba7a6c0586fcc83992bbbc1776affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before bf415bfe7573596ac213b4fd1da9e62cfc9a9413affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before ff484163dfb61b58f23e4dbd007de1094427669caffected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 42b78c8cc774b47023d6d16d96d54cc7015e4a07affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 9be921854e983a81a0aeeae5febcd87093086e46affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 6147745d43ff4e0d2c542e5b93e398ef0ee4db00affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 72d0240b0ee4794efc683975c213e4b384fea733affected · git
    • 289507d3364f96f4b8814726917d572f71350d87 and later · before 7e01c7f7046efc2c7c192c3619db43292b98e997affected · git
    • before 3.16not affected · semver
Affected versions · NVD (8)

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

  • linux linux kernel3.16 and later · before 4.14.317
  • linux linux kernel4.15 and later · before 4.19.285
  • linux linux kernel4.20 and later · before 5.4.245
  • linux linux kernel5.5 and later · before 5.10.181
  • linux linux kernel5.11 and later · before 5.15.114
  • linux linux kernel5.16 and later · before 6.1.31
  • linux linux kernel6.2 and later · before 6.3.5
  • linux linux kernel6.4

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.37-16.1.37-1
Debian:13linuxbefore 6.3.7-16.3.7-1

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-2023-53663Oct 7, 2025 · KVM: nSVM: Check instead of asserting on nested TSC scaling support
    22Monitor
  • ← EarlierCVE-2023-53664Oct 7, 2025 · OPP: Fix potential null ptr dereference in dev_pm_opp_get_required_pstate()
    22Monitor
  • Later →CVE-2023-53668Oct 7, 2025 · ring-buffer: Fix deadloop issue on reading trace_pipe
    28Monitor

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 Linux2334ff0b343ba6ba7a6c0586fcc83992bbbc1776Vendor (CNA)
Linux Linux42b78c8cc774b47023d6d16d96d54cc7015e4a07Vendor (CNA)
Linux Linux6147745d43ff4e0d2c542e5b93e398ef0ee4db00Vendor (CNA)
Linux Linux72d0240b0ee4794efc683975c213e4b384fea733Vendor (CNA)
Linux Linux7e01c7f7046efc2c7c192c3619db43292b98e997Vendor (CNA)
Linux Linux9be921854e983a81a0aeeae5febcd87093086e46Vendor (CNA)
Linux Linuxbf415bfe7573596ac213b4fd1da9e62cfc9a9413Vendor (CNA)
Linux Linuxff484163dfb61b58f23e4dbd007de1094427669cVendor (CNA)
debian:linux6.1.37-1 · 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.

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
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-476 · NULL Pointer Dereference

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.

References

Show all references (7 more)

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

All records