Heimdall Security Logo

CVE-2026-31649

Vulnérabilité critique dans Linux (Linux)

CVSS 9.8 · Critique
EPSS 0.5%
Linux•Linux•Versions : <51f4e090b9f87b40c21b6daadb5c06e6c0a07b67, <=6.1.*, <3.2, <=6.12.*, 6.18.23, 286a837217204b1ef105e3a554d0757e4fdfaac1, 0, 7.0, <6fca757c20396dc2e604dcc61922264e9e3dc803, <a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f, <=5.10.*, <=6.6.*, <=6.19.*, 6.1.169, 5.15.203, <=6.18.*, <b7b8012193fd98236d7ae05d4b553f010a77b2ef, 3.2, <2c91b39912278d0878f9ba60ba04d2518b18a08d, <513e06735f5be575b409d195822195348b164e48, <10d12b9240ebf96c785f0e2e4228318cd5f3a3eb, 6.6.135, 6.19.13, <=*, 5.10.253, <=5.15.*, <275bdf762e82082f064e60a92448fa2ac43cf95b, 6.12.82

Description

In the Linux kernel, the following vulnerability has been resolved: net: stmmac: fix integer underflow in chain mode The jumbo_frm() chain-mode implementation unconditionally computes len = nopaged_len - bmax; where nopaged_len = skb_headlen(skb) (linear bytes only) and bmax is BUF_SIZE_8KiB or BUF_SIZE_2KiB. However, the caller stmmac_xmit() decides to invoke jumbo_frm() based on skb->len (total length including page fragments): is_jumbo = stmmac_is_jumbo_frm(priv, skb->len, enh_desc); When a packet has a small linear portion (nopaged_len <= bmax) but a large total length due to page fragments (skb->len > bmax), the subtraction wraps as an unsigned integer, producing a huge len value (~0xFFFFxxxx). This causes the while (len != 0) loop to execute hundreds of thousands of iterations, passing skb->data + bmax * i pointers far beyond the skb buffer to dma_map_single(). On IOMMU-less SoCs (the typical deployment for stmmac), this maps arbitrary kernel memory to the DMA engine, constituting a kernel memory disclosure and potential memory corruption from hardware. Fix this by introducing a buf_len local variable clamped to min(nopaged_len, bmax). Computing len = nopaged_len - buf_len is then always safe: it is zero when the linear portion fits within a single descriptor, causing the while (len != 0) loop to be skipped naturally, and the fragment loop in stmmac_xmit() handles page fragments afterward.

Gravité et risque d'exploitation

CVE-2026-31649 obtient un score CVSS de 9.8/10, soit une gravité critique. Selon le modèle EPSS, la probabilité qu'elle soit exploitée dans les 30 prochains jours est de 0.46 %, ce qui la place devant 38.4 % des CVE référencées.

Que faire ?

  • Vérifiez si Linux (versions <51f4e090b9f87b40c21b6daadb5c06e6c0a07b67, <=6.1.*, <3.2, <=6.12.*, 6.18.23, 286a837217204b1ef105e3a554d0757e4fdfaac1, 0, 7.0, <6fca757c20396dc2e604dcc61922264e9e3dc803, <a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f, <=5.10.*, <=6.6.*, <=6.19.*, 6.1.169, 5.15.203, <=6.18.*, <b7b8012193fd98236d7ae05d4b553f010a77b2ef, 3.2, <2c91b39912278d0878f9ba60ba04d2518b18a08d, <513e06735f5be575b409d195822195348b164e48, <10d12b9240ebf96c785f0e2e4228318cd5f3a3eb, 6.6.135, 6.19.13, <=*, 5.10.253, <=5.15.*, <275bdf762e82082f064e60a92448fa2ac43cf95b, 6.12.82) 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