> CVE-2025-21920 [HIGH]

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PUBLISHED
2025-04-01 16:15
MODIFIED
2025-10-01 21:16
CVSS_SCORE V3
7.1
EPSS (Prob. Exploit)
0.24%
Top 85.5%
DATA SOURCES:
NVD 🔗 2025-10-18 RED HAT 🔗 2025-10-18 CVE PROJECT 🔗 2026-01-19 FIRST EPSS 🔗 2026-11-08 OSV 🔗 2026-11-08 MSRC 🔗 2026-03-02

> DESCRIPTION

In the Linux kernel, the following vulnerability has been resolved: vlan: enforce underlying device type Currently, VLAN devices can be created on top of non-ethernet devices. Besides the fact that it doesn't make much sense, this also causes a bug which leaks the address of a kernel function to usermode. When creating a VLAN device, we initialize GARP (garp_init_applicant) and MRP (mrp_init_applicant) for the underlying device. As part of the initialization process, we add the multicast address of each applicant to the underlying device, by calling dev_mc_add. __dev_mc_add uses dev->addr_len to determine the length of the new multicast address. This causes an out-of-bounds read if dev->addr_len is greater than 6, since the multicast addresses provided by GARP and MRP are only 6 bytes long. This behaviour can be reproduced using the following commands: ip tunnel add gretest mode ip6gre local ::1 remote ::2 dev lo ip l set up dev gretest ip link add link gretest name vlantest type vlan id 100 Then, the following command will display the address of garp_pdu_rcv: ip maddr show | grep 01:80:c2:00:00:21 Fix the bug by enforcing the type of the underlying device during VLAN device initialization.

> AFFECTED_PRODUCTS

Red Hat - Red Hat Enterprise Linux 9
Version: 5.14.0

> CVSS V3 METRICS

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

> MÉTRIQUES CVSS DÉTAILLÉES

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
Métrique Valeur Interprétation
AV (Vecteur d'Attaque)
Attack Vector
Local (L)
Exploit nécessite un accès local au système
AC (Complexité d'Attaque)
Attack Complexity
Low (L)
Peu de conditions requises pour exploiter
PR (Privilèges Requis)
Privileges Required
Low (L)
Authentifié avec compte utilisateur basique
UI (Interaction Utilisateur)
User Interaction
None (N)
Aucune interaction utilisateur nécessaire
S (Périmètre)
Scope
Unchanged (U)
Impact reste dans le périmètre du composant compromis
C (Impact Confidentialité)
Confidentiality Impact
High (H)
Divulgation totale d'informations
I (Impact Intégrité)
Integrity Impact
None (N)
Aucune modification de données possible
A (Impact Disponibilité)
Availability Impact
High (H)
Interruption totale du service possible

> RÉSUMÉ DES IMPACTS

Confidentialité
High
Divulgation totale d'informations
Intégrité
None
Aucune modification de données possible
Disponibilité
High
Interruption totale du service possible

> RED HAT SECURITY ADVISORIES

Red Hat Security Advisory: kernel security update
An update for kernel is now available for Red Hat Enterprise Linux 9. Red Hat Product Security has rated this update as having a security impact of Important. A Common Vulnerability Scoring System (C...

> RED HAT SEVERITY ASSESSMENT

THREAT SEVERITY
Moderate

> OSV (GOOGLE OPEN SOURCE VULNERABILITIES)

vlan: enforce underlying device type

AFFECTED PACKAGES:
Unknown / Unknown
Linux / Kernel

> HISTORIQUE DES MODIFICATIONS

Première apparition
01/04/2025 16:15
Source: NVD
📊 ENRICHISSEMENT 18/10/2025 15:02
CVEPROJECT
Champ modifié: CVE Project
Ancienne valeur:
Non
Nouvelle valeur:
Oui
📊 ENRICHISSEMENT 18/10/2025 12:18
REDHAT
Champ modifié: Sévérité Red Hat
Ancienne valeur:
N/A
Nouvelle valeur:
{ "threat_severity": "Moderate", "severity_scale": null }
📊 ENRICHISSEMENT 18/10/2025 12:18
REDHAT
Champ modifié: Red Hat
Ancienne valeur:
Non
Nouvelle valeur:
Oui
Total des modifications: 3 Dernière mise à jour: 1 year ago
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