CVE-2021-0242
Vulnérabilité moyenne dans Junos OS (Juniper Networks)
Description
A vulnerability due to the improper handling of direct memory access (DMA) buffers on EX4300 switches on Juniper Networks Junos OS allows an attacker sending specific unicast frames to trigger a Denial of Service (DoS) condition by exhausting DMA buffers, causing the FPC to crash and the device to restart. The DMA buffer leak is seen when receiving these specific, valid unicast frames on an interface without Layer 2 Protocol Tunneling (L2PT) or dot1x configured. Interfaces with either L2PT or dot1x configured are not vulnerable to this issue. When this issue occurs, DMA buffer usage keeps increasing and the following error log messages may be observed: Apr 14 14:29:34.360 /kernel: pid 64476 (pfex_junos), uid 0: exited on signal 11 (core dumped) Apr 14 14:29:33.790 init: pfe-manager (PID 64476) terminated by signal number 11. Core dumped! The DMA buffers on the FPC can be monitored by the executing vty command 'show heap': ID Base Total(b) Free(b) Used(b) % Name -- ---------- ----------- ----------- ----------- --- ----------- 0 4a46000 268435456 238230496 30204960 11 Kernel 1 18a46000 67108864 17618536 49490328 73 Bcm_sdk 2 23737000 117440512 18414552 99025960 84 DMA buf <<<<< keeps increasing 3 2a737000 16777216 16777216 0 0 DMA desc This issue affects Juniper Networks Junos OS on the EX4300: 17.3 versions prior to 17.3R3-S11; 17.4 versions prior to 17.4R2-S13, 17.4R3-S4; 18.1 versions prior to 18.1R3-S12; 18.2 versions prior to 18.2R2-S8, 18.2R3-S7; 18.3 versions prior to 18.3R3-S4; 18.4 versions prior to 18.4R1-S8, 18.4R2-S7, 18.4R3-S7; 19.1 versions prior to 19.1R1-S6, 19.1R2-S2, 19.1R3-S4; 19.2 versions prior to 19.2R1-S6, 19.2R3-S2; 19.3 versions prior to 19.3R3-S2; 19.4 versions prior to 19.4R2-S3, 19.4R3-S1; 20.1 versions prior to 20.1R2; 20.2 versions prior to 20.2R2-S1, 20.2R3; 20.3 versions prior to 20.3R1-S1, 20.3R2.
Gravité et risque d'exploitation
CVE-2021-0242 obtient un score CVSS de 6.5/10, soit une gravité moyenne. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.40 %, ce qui la place devant 33.2 % des CVE référencées.
Que faire ?
- Vérifiez si Junos OS (versions 19.2, <17.3R3-S11, <18.1R3-S12, 19.3, <19.4R2-S3, 19.4R3-S1, 20.1, 18.2, 20.3, <19.1R1-S6, 19.1R2-S2, 19.1R3-S4, <20.2R2-S1, 20.2R3, <17.4R2-S13, 17.4R3-S4, 18.3, 19.1, 18.1, 17.4, 18.4, 17.3, 19.4, <19.2R1-S6, 19.2R3-S2, <19.3R3-S2, <20.3R1-S1, 20.3R2, <20.1R2, <18.2R2-S8, 18.2R3-S7, 20.2, <18.3R3-S4, <18.4R1-S8, 18.4R2-S7, 18.4R3-S7) 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.