{
  "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"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  calipso: keep BIG TCP payload_len in calipso_skbuff_setattr()  calipso_skbuff_setattr() adjusts payload_len by the length of the option it inserts or resizes:  \tpayload = ntohs(ip6_hdr-\u003epayload_len); \tip6_hdr-\u003epayload_len = htons(payload + len_delta);  GRO can build BIG TCP packets larger than IPV6_MAXPLEN, and stores payload_len == 0 for them; ipv6_payload_len() then falls back to skb-\u003elen.  For such a packet forwarded to a destination mapped to CALIPSO, the code above writes len_delta (or 65536 + len_delta when shrinking) into payload_len, and ipv6_payload_len() no longer falls back to skb-\u003elen.  nf_tables, conntrack and sch_cake rely on it.  The same arithmetic also wraps when a packet grows past IPV6_MAXPLEN, and a BIG TCP packet that shrinks below IPV6_MAXPLEN should get its real length back.  Set payload_len from the skb length with ipv6_set_payload_len(), which stores 0 above IPV6_MAXPLEN and the real length otherwise, as ipv6_gro_complete() does.  The network header was just reset to skb-\u003edata, so skb-\u003elen - sizeof(*ip6_hdr) is the payload length.  Tested on one kernel (arm64, QEMU) with SELinux permissive, a minimal mdp-generated policy (network_peer_controls=1), \"netlabelctl calipso add pass doi:16\" and a NetLabel mapping of fd00:2::/64 to CALIPSO DOI 16.  calipso_skbuff_setattr() was called through netlbl_skbuff_setattr() from a test-only debugfs hook (not part of this patch) adding a level-only label; payload_len after the call:    case                         before fix   after fix   real length   1000, unlabeled                    1016        1016          1016   70000 GSO, payload_len 0             16           0         70016   65530 GSO, grows past MAXPLEN        10           0         65546   65540 GSO with a 24 byte hop   header, shrinks below MAXPLEN     65528       65532         65532   1000 with a 24 byte hop header      992         992           992  (0 means ipv6_payload_len() returns the real length.)  On the forward path, with a client injecting unlabeled UDP through a router to a server, the router adds the CALIPSO option and the server delivers all datagrams (Udp6InDatagrams 5, Ip6InTruncatedPkts 0) with this patch.",
  "id": "DEBIAN-CVE-2026-99191",
  "modified": "2026-10-29T05:47:32.330706400Z",
  "published": "2026-10-28T11:17:40.080Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-99191"
    }
  ],
  "upstream": [
    "CVE-2026-99191"
  ]
}