{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.113-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.2.10-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  net: extend IPv6 exthdr detection of tunneled packets  Commit c4336a07eb6b (\"net: correctly handle tunneled traffic on IPV6_CSUM GSO fallback\") split skb_gso_has_extension_hdr() into mutually exclusive branches on skb-\u003eencapsulation. This did not yet address all paths:  1. With skb-\u003eencapsulation set, the outer header is not checked. IPv6    tunnels such as ip6_gre and ip6_tunnel add an outer Destination    Options header by default (encap_limit). Their GSO packets skip    software GSO, then skb_csum_hwoffload_help() sees the outer extension    header and calls skb_checksum_help() on the GSO skb, which warns and    drops it.  2. Tunnels over IPv6 without an outer transport header, such as    ip6_tunnel, leave skb-\u003etransport_header at the inner transport    header. skb_network_header_len() then spans the outer IPv6, tunnel    and inner IP headers, a false positive.  3. UDP tunnels without an inner network header, such as SCTP-in-UDP or    PSP, have no inner IPv6 header to check. Decide on the outer header    alone.  4. Directly dereferencing inner_ip_hdr(skb)-\u003eversion without    skb_header_pointer() is unsafe.  Instead, check ipv6_ext_hdr(nexthdr) on the outer IPv6 header and, if set, on the inner IPv6 header. Read the headers with skb_header_pointer(). Keep the skb_network_header_len() check when !skb-\u003eencapsulation to also catch encapsulated packets without skb-\u003eencapsulation (e.g., virtio).  Use the same helper in skb_csum_hwoffload_help(). Its open coded test has the false positive of (2) and ignores the inner header.  Background: checksum offload of tunneled packets invariants:  Non-GSO skb: - If the inner packet is CHECKSUM_PARTIAL, Local Checksum Offload computes   the outer checksum in software and the device offloads only the inner L4   checksum. - If the inner packet is CHECKSUM_NONE (e.g., SCTP-in-UDP, ESP-in-UDP,   Remote Checksum Offload), the device offloads the outer UDP or GRE   checksum instead.  GSO skb: - A device with NETIF_F_GSO_UDP_TUNNEL_CSUM or NETIF_F_GSO_GRE_CSUM   computes both inner and outer checksums per segment.   The outer checksum is seeded with only the pseudo-header checksum.  A NETIF_F_IPV6_CSUM device must parse through the outer headers to reach the inner ones.",
  "id": "DEBIAN-CVE-2026-98852",
  "modified": "2026-10-19T04:47:46.554062347Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-98852"
    }
  ],
  "upstream": [
    "CVE-2026-98852"
  ]
}