{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.170-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.85-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.19.13-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "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-\u003elen (total length including page fragments):      is_jumbo = stmmac_is_jumbo_frm(priv, skb-\u003elen, enh_desc);  When a packet has a small linear portion (nopaged_len \u003c= bmax) but a large total length due to page fragments (skb-\u003elen \u003e 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-\u003edata + 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.",
  "id": "DEBIAN-CVE-2026-31649",
  "modified": "2026-09-14T16:47:34.717615861Z",
  "published": "2026-04-24T15:16:44.330Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-31649"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "upstream": [
    "CVE-2026-31649"
  ]
}