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CVE Record

CVE-2023-46838: Linux: netback processing of zero-length transmit fragment

Transmit requests in Xen's virtual network protocol can consist of multiple parts. While not really useful, except for the initial part any of them may be of zero length, i.e. carry no data at all. Besides a certain initial portion of the to be transferred data, these parts are directly translated into what Linux calls SKB fragments. Such converted request parts can, when for a particular SKB they are all of length zero, lead to a de-reference of NULL in core networking code.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2023-46838 can let malformed zero-length transmit fragments in Xen virtual networking crash Linux networking code. The described impact is availability only: service disruption or host/network stack crash, not data theft or tampering. Urgency is highest for Linux systems providing Xen netback networking to guests.

Executive priority

Treat as a high-priority availability issue for Xen virtualization infrastructure. It is not described as data compromise, but a host networking crash can affect many workloads and service-level commitments.

Technical view

Linux netback converts parts of Xen virtual network transmit requests into SKB fragments. If converted fragments for a particular SKB are all zero length, core networking code can dereference NULL. The CVE is CWE-476 with CVSS 7.5, scored for high availability impact and no confidentiality or integrity impact.

Likely exposure

Exposure is most likely on Linux systems using Xen virtual network backend processing. The source bundle does not enumerate affected kernel versions and points readers to Xen XSA-448 and distribution advisories for applicability.

Exploitation context

The bundle does not report active exploitation and marks KEV false. Exploitation would require reaching the Xen virtual network transmit path handled by Linux netback; the provided evidence does not support treating this as general internet-exposed remote code execution.

Researcher notes

Key uncertainty is version scope: the bundle lists Linux as affected but defers versions to XSA-448. Focus validation on the netback transmit path, zero-length fragment handling, and whether downstream kernel packages include the advisory fix.

Mitigation direction

  • Review Xen XSA-448 for affected configurations and vendor guidance.
  • Apply Linux kernel or distribution updates referenced by Xen, Fedora, or Debian advisories.
  • Prioritize multi-tenant Xen hosts and systems with untrusted guest workloads.
  • If patching is delayed, follow vendor-published mitigations; do not invent generic network filtering controls.

Validation and detection

  • Inventory Linux hosts that provide Xen virtual network backend services.
  • Map kernel and package versions against Xen XSA-448 and distribution advisories.
  • Confirm patched packages are installed through normal configuration management evidence.
  • Review availability incidents or kernel crashes on exposed Xen hosts since publication.
Prepared
Confidence
medium
Sources
7

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

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cwe · low confidence lookup

CWE-476: Exact CWE lookup

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cve · low confidence lookup

CVE-2023-46838 mapping review

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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
0Timeline events
0ADP providers
6Source links

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:H3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2023-46838Attack 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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxconsult Xen advisory XSA-448unknown
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.

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