LiveActive security incident?Get immediate response
CVE Record

CVE-2024-27405: usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs

In the Linux kernel, the following vulnerability has been resolved: usb: gadget: ncm: Avoid dropping datagrams of properly parsed NTBs It is observed sometimes when tethering is used over NCM with Windows 11 as host, at some instances, the gadget_giveback has one byte appended at the end of a proper NTB. When the NTB is parsed, unwrap call looks for any leftover bytes in SKB provided by u_ether and if there are any pending bytes, it treats them as a separate NTB and parses it. But in case the second NTB (as per unwrap call) is faulty/corrupt, all the datagrams that were parsed properly in the first NTB and saved in rx_list are dropped. Adding a few custom traces showed the following: [002] d..1 7828.532866: dwc3_gadget_giveback: ep1out: req 000000003868811a length 1025/16384 zsI ==> 0 [002] d..1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb toprocess: 1025 [002] d..1 7828.532867: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb seq: 0xce67 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x400 [002] d..1 7828.532868: ncm_unwrap_ntb: K: ncm_unwrap_ntb ndp_len: 0x10 [002] d..1 7828.532869: ncm_unwrap_ntb: K: Parsed NTB with 1 frames In this case, the giveback is of 1025 bytes and block length is 1024. The rest 1 byte (which is 0x00) won't be parsed resulting in drop of all datagrams in rx_list. Same is case with packets of size 2048: [002] d..1 7828.557948: dwc3_gadget_giveback: ep1out: req 0000000011dfd96e length 2049/16384 zsI ==> 0 [002] d..1 7828.557949: ncm_unwrap_ntb: K: ncm_unwrap_ntb nth: 1751999342 [002] d..1 7828.557950: ncm_unwrap_ntb: K: ncm_unwrap_ntb blk_len: 0x800 Lecroy shows one byte coming in extra confirming that the byte is coming in from PC: Transfer 2959 - Bytes Transferred(1025) Timestamp((18.524 843 590) - Transaction 8391 - Data(1025 bytes) Timestamp(18.524 843 590) --- Packet 4063861 Data(1024 bytes) Duration(2.117us) Idle(14.700ns) Timestamp(18.524 843 590) --- Packet 4063863 Data(1 byte) Duration(66.160ns) Time(282.000ns) Timestamp(18.524 845 722) According to Windows driver, no ZLP is needed if wBlockLength is non-zero, because the non-zero wBlockLength has already told the function side the size of transfer to be expected. However, there are in-market NCM devices that rely on ZLP as long as the wBlockLength is multiple of wMaxPacketSize. To deal with such devices, it pads an extra 0 at end so the transfer is no longer multiple of wMaxPacketSize.

HighCVSS 7.5Not KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This flaw can make Linux devices using USB NCM tethering drop valid network traffic when a host sends an extra trailing byte. The impact is availability, not data theft or code execution, based on the provided sources. It matters most for embedded, mobile, or appliance products that expose Linux USB gadget networking.

Executive priority

Prioritize remediation for shipped products or operational devices that depend on USB tethering for management, connectivity, or field service. For typical server estates, urgency is lower unless USB gadget networking is enabled. Treat as an availability reliability issue with business impact where tethered connectivity is critical.

Technical view

In Linux USB gadget NCM handling, leftover bytes after a valid NTB could be treated as another NTB. If that trailing fragment was invalid, already parsed datagrams in rx_list were dropped. The source describes Windows 11 appending a zero byte for compatibility when block length aligns with max packet size.

Likely exposure

Exposure is likely limited to Linux systems acting as USB NCM gadget devices, especially tethering scenarios with Windows 11 hosts. General Linux servers and clients are unlikely to be exposed unless they enable this USB gadget networking role.

Exploitation context

No active exploitation is identified in the provided bundle, and KEV is false. The scenario described is interoperability-triggered packet loss from a host-side extra byte. CVSS rates availability impact high with no confidentiality or integrity impact.

Researcher notes

The evidence points to Linux USB gadget NCM datagram dropping after parsing a valid NTB plus trailing byte. The bundle lists CWE-476, but the description primarily documents packet loss logic. Avoid assuming remote internet exposure, code execution, or broader USB classes without additional vendor evidence.

Mitigation direction

  • Update affected Linux kernels or vendor packages to versions containing the listed stable fixes.
  • Check Debian LTS advisories if running Debian-supported kernels.
  • If patching is delayed, reduce reliance on USB NCM gadget tethering where operationally possible.
  • Track vendor guidance for your device kernel and any backported fix status.

Validation and detection

  • Inventory products and devices that enable Linux USB gadget NCM or tethering modes.
  • Compare kernel versions against vendor advisories and upstream stable fix commits.
  • Confirm whether your distribution kernel has backported the relevant Linux stable patch.
  • Review support logs for USB NCM packet loss during Windows 11 tethering scenarios.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-476: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2024-27405 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
2ADP providers
11Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2024-27405Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28c, 9f6ce4240a2bf456402c15c06768059e5973f28cunaffected
LinuxLinux2.6.38, 0, 4.19.308, 5.4.270, 5.10.211, 5.15.150, 6.1.80, 6.6.19, 6.7.7, 6.8affected
Weakness

CWE details

CWE-476

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-476 · source CWE mapping

NULL Pointer Dereference

NULL Pointer Dereference represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs