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CVE-2025-21920

Vulnérabilité élevée dans Linux (Linux)

CVSS 7.1 · Élevée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, 6.6.83, 22bedad3ce112d5ca1eaf043d4990fa2ed698c87, <=6.12.*, 6.1.131, 0, <7f1564b2b2072b7aa1ac75350e9560a07c7a44fd, <3561442599804905c3defca241787cd4546e99a7, 6.12.19, <b33a534610067ade2bdaf2052900aaad99701353, 6.13.7, 6.14, <=5.10.*, <=6.6.*, <0fb7aa04c19eac4417f360a9f7611a60637bdacc, <fa40ebef69234e39ec2d26930d045f2fb9a8cb2b, <=5.4.*, 5.4.291, <2.6.35, <30e8aee77899173a82ae5ed89f536c096f20aaeb, 5.15.179, <=*, <=5.15.*, 5.10.235, <5a515d13e15536e82c5c7c83eb6cf5bc4827fee5, <b6c72479748b7ea09f53ed64b223cee6463dc278, <=6.13.*, 2.6.35

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.

Gravité et risque d'exploitation

CVE-2025-21920 obtient un score CVSS de 7.1/10, soit une gravité élevée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.23 %, ce qui la place devant 13.0 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, 6.6.83, 22bedad3ce112d5ca1eaf043d4990fa2ed698c87, <=6.12.*, 6.1.131, 0, <7f1564b2b2072b7aa1ac75350e9560a07c7a44fd, <3561442599804905c3defca241787cd4546e99a7, 6.12.19, <b33a534610067ade2bdaf2052900aaad99701353, 6.13.7, 6.14, <=5.10.*, <=6.6.*, <0fb7aa04c19eac4417f360a9f7611a60637bdacc, <fa40ebef69234e39ec2d26930d045f2fb9a8cb2b, <=5.4.*, 5.4.291, <2.6.35, <30e8aee77899173a82ae5ed89f536c096f20aaeb, 5.15.179, <=*, <=5.15.*, 5.10.235, <5a515d13e15536e82c5c7c83eb6cf5bc4827fee5, <b6c72479748b7ea09f53ed64b223cee6463dc278, <=6.13.*, 2.6.35) est présent sur votre parc.
  • Appliquez le correctif ou la version corrigée indiqués dans les références de l'éditeur.
  • À défaut de correctif, limitez l'exposition (filtrage réseau, désactivation du composant).
  • Automatisez la détection : les agents CVE Heimdall (gratuits, open source) corrèlent l'inventaire de vos serveurs avec la base CVE.

Références

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