Heimdall Security Logo

CVE-2026-63836

Vulnérabilité non évaluée dans Linux (Linux)

CVSS 0.0 · Non évaluée
EPSS 0.2%
Linux•Linux•Versions : <=6.1.*, <=6.12.*, <585616dab0aa9c45bc11b2c8082ca78533bc00e9, 6.6.144, 5.15.211, 0, <=7.1.*, 5.10.260, <7d2a44bc6bbe39aed03c68864aa0e54e04a50278, <=5.10.*, <=6.6.*, 6.12.95, <ac229c86e49fdb96d91f51bc2fa37a9c4f58c44f, <1381b021bf886b793fa5ffb895a8efae7ba0318f, <33ccd52f3cc9ed46ce395199f89aa3234dc83314, <=6.18.*, 6.1.177, 6.18.38, 33a3bb4a3345bb511f9c69c913da95d4693e2a4e, 4.8, <cd74176cf1685f35a2e5f212d15748bbfecb53b6, <=*, <=5.15.*, 7.1.3, <4.8, <35264c4d46067d6312871488c810cef387f8c1f6, <d08b69da40a101df1e28bfe1e8fa7a09ffa41107, 7.2

Description

In the Linux kernel, the following vulnerability has been resolved: batman-adv: tp_meter: avoid divide-by-zero for dec_cwnd The cwnd is always MSS <= cwnd <= 0x20000000. But the calculation in batadv_tp_update_cwnd() assumes unsigned 32 bit arithmetics. ((mss * 8) ** 2) / (cwnd * 8) In case cwnd is actually 0x20000000, it will be shifted by 3 bit to the left end up at 0x100000000 or U32_MAX + 1. It will therefore wrap around and be 0 - resulting in: ((mss * 8) ** 2) / 0 This is of course invalid and cannot be calculated. The calculation should must be simplified to avoid this overflow: (mss ** 2) * 8 / cwnd It will keep the precision enhancement from the scaling (by 8) but avoid the overflow in the divisor. In theory, there could still be an overflow in the dividend. It is at the moment fixed to BATADV_TP_PLEN in batadv_tp_recv_ack() - so it is not an imminent problem. But allowing it to use the whole u32 bit range, would mean that it can still use up to 67 bits. To keep this calculation safe for 32 bit arithmetic, mss must never use more than floor((32 - 3) / 2) bits - or in other words: must never be larger than 16383.

Gravité et risque d'exploitation

CVE-2026-63836 obtient un score CVSS de 0.0/10, soit une gravité non évaluée. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.17 %, ce qui la place devant 6.5 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <=6.1.*, <=6.12.*, <585616dab0aa9c45bc11b2c8082ca78533bc00e9, 6.6.144, 5.15.211, 0, <=7.1.*, 5.10.260, <7d2a44bc6bbe39aed03c68864aa0e54e04a50278, <=5.10.*, <=6.6.*, 6.12.95, <ac229c86e49fdb96d91f51bc2fa37a9c4f58c44f, <1381b021bf886b793fa5ffb895a8efae7ba0318f, <33ccd52f3cc9ed46ce395199f89aa3234dc83314, <=6.18.*, 6.1.177, 6.18.38, 33a3bb4a3345bb511f9c69c913da95d4693e2a4e, 4.8, <cd74176cf1685f35a2e5f212d15748bbfecb53b6, <=*, <=5.15.*, 7.1.3, <4.8, <35264c4d46067d6312871488c810cef387f8c1f6, <d08b69da40a101df1e28bfe1e8fa7a09ffa41107, 7.2) 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

Rechercher une autre CVE