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.

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required Low

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00036.

Key SSVC decision points have not yet been added.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions
Linux Linux unaffected
Version Status Constraints
289507d3364f96f4b8814726917d572f71350d87 affected < 2334ff0b343ba6ba7a6c0586fcc83992bbbc1776
289507d3364f96f4b8814726917d572f71350d87 affected < bf415bfe7573596ac213b4fd1da9e62cfc9a9413
289507d3364f96f4b8814726917d572f71350d87 affected < ff484163dfb61b58f23e4dbd007de1094427669c
289507d3364f96f4b8814726917d572f71350d87 affected < 42b78c8cc774b47023d6d16d96d54cc7015e4a07
289507d3364f96f4b8814726917d572f71350d87 affected < 9be921854e983a81a0aeeae5febcd87093086e46
289507d3364f96f4b8814726917d572f71350d87 affected < 6147745d43ff4e0d2c542e5b93e398ef0ee4db00
289507d3364f96f4b8814726917d572f71350d87 affected < 72d0240b0ee4794efc683975c213e4b384fea733
289507d3364f96f4b8814726917d572f71350d87 affected < 7e01c7f7046efc2c7c192c3619db43292b98e997
Linux Linux affected
Version Status Constraints
3.16 affected —
0 unaffected < 3.16
4.14.317 unaffected ≤ 4.14.*
4.19.285 unaffected ≤ 4.19.*
5.4.245 unaffected ≤ 5.4.*
5.10.181 unaffected ≤ 5.10.*
5.15.114 unaffected ≤ 5.15.*
6.1.31 unaffected ≤ 6.1.*
6.3.5 unaffected ≤ 6.3.*
6.4 unaffected ≤ *

Configuration 1 [-]

OR cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc3:*:*:*:*:*:*

No data.

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Fixes

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Workaround

No workaround given by the vendor.

References
Link Providers
https://git.kernel.org/stable/c/2334ff0b343ba6ba7a6c0586fcc83992bbbc1776 cve-icon cve-icon
https://git.kernel.org/stable/c/42b78c8cc774b47023d6d16d96d54cc7015e4a07 cve-icon cve-icon
https://git.kernel.org/stable/c/6147745d43ff4e0d2c542e5b93e398ef0ee4db00 cve-icon cve-icon
https://git.kernel.org/stable/c/72d0240b0ee4794efc683975c213e4b384fea733 cve-icon cve-icon
https://git.kernel.org/stable/c/7e01c7f7046efc2c7c192c3619db43292b98e997 cve-icon cve-icon
https://git.kernel.org/stable/c/9be921854e983a81a0aeeae5febcd87093086e46 cve-icon cve-icon
https://git.kernel.org/stable/c/bf415bfe7573596ac213b4fd1da9e62cfc9a9413 cve-icon cve-icon
https://git.kernel.org/stable/c/ff484163dfb61b58f23e4dbd007de1094427669c cve-icon cve-icon
https://lore.kernel.org/linux-cve-announce/2025100704-CVE-2023-53667-9b2e@gregkh/T cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2023-53667 cve-icon
https://www.cve.org/CVERecord?id=CVE-2023-53667 cve-icon
History

Tue, 03 Feb 2026 22:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-476
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc1:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc2:*:*:*:*:*:*
cpe:2.3:o:linux:linux_kernel:6.4:rc3:*:*:*:*:*:*
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

 cvssV3_1

{'score': 5.5, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Wed, 08 Oct 2025 13:45:00 +0000

Type Values Removed Values Added
First Time appeared Linux
Linux linux Kernel
Vendors & Products Linux
Linux linux Kernel

Wed, 08 Oct 2025 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Important

Tue, 07 Oct 2025 15:30:00 +0000

Type Values Removed Values Added
Description 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.
Title net: cdc_ncm: Deal with too low values of dwNtbOutMaxSize
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2025-10-07T15:21:25.185Z

Reserved: 2025-10-07T15:16:59.662Z

Link: CVE-2023-53667

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Analyzed

Published: 2025-10-07T16:15:50.513

Modified: 2026-02-03T22:23:57.777

Link: CVE-2023-53667

cve-icon Redhat

Severity : Important

Publid Date: 2025-10-07T00:00:00Z

Links: CVE-2023-53667 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-08T13:35:29Z

Weaknesses