{
  "affected": [
    {
      "ranges": [
        {
          "events": [
            {
              "introduced": "56af5e749f20c3a540310c207dcc373f4f09156e"
            },
            {
              "fixed": "985a37781ade19061400100c2ba0f43979dd4d63"
            },
            {
              "fixed": "d896843d8d925f0adbba319020595cfb1a7bcd57"
            },
            {
              "fixed": "0675cff3c2924eb9b80d9dd250cf56a1140af157"
            },
            {
              "fixed": "e8a2027b7e686784a69b2dfcee841d779919f313"
            },
            {
              "fixed": "1719865b20b22c88d2a55e922eff5ca31b0841f6"
            },
            {
              "fixed": "62126464f3a6159c0a3dd89e196ba65bfeb0afc6"
            },
            {
              "fixed": "81d0d1e64f30d9989c829c0953cd6e6c68d9c5fb"
            }
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "type": "GIT"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Linux",
        "name": "Kernel"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "5.15.0"
            },
            {
              "fixed": "5.15.221"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "5.16.0"
            },
            {
              "fixed": "6.1.188"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.2.0"
            },
            {
              "fixed": "6.6.157"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.7.0"
            },
            {
              "fixed": "6.12.110"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.13.0"
            },
            {
              "fixed": "6.18.52"
            }
          ],
          "type": "ECOSYSTEM"
        },
        {
          "events": [
            {
              "introduced": "6.19.0"
            },
            {
              "fixed": "7.2.6"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "cna_assigner": "Linux",
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90078.json"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_skbmod: fix length calculations and avoid invalid header warnings\n\nsyzbot reported a warning in skb_network_header_len() triggered\nby tcf_skbmod_act():\n\n  !skb_transport_header_was_set(skb)\n  WARNING: CPU: 0 PID: 14949 at include/linux/skbuff.h:3243 skb_network_header_len include/linux/skbuff.h:3243 [inline]\n  WARNING: CPU: 0 PID: 14949 at net/sched/act_skbmod.c:55 tcf_skbmod_act+0xfe8/0x1810 net/sched/act_skbmod.c:55\n\nThere are a few issues in tcf_skbmod_act():\n\n1. Calling skb_network_header_len() assumes skb-\u003etransport_header is set,\n   which is not guaranteed when tcf_skbmod_act() runs at TC ingress.\n2. Unconditionally calling skb_mac_header_len() at the beginning of\n   tcf_skbmod_act() triggers a warning on L3 devices (e.g. TUN) where the\n   MAC header is unset, evaluating to an underflowed garbage length.\n3. On TC ingress, skb-\u003edata points to the network header. Adding the MAC\n   header length to the IP header length causes skb_ensure_writable() to\n   request more bytes than the actual IP packet length, dropping valid\n   short packets (e.g. 28-byte UDP/IPv4 packets).\n\nFix these by:\n- Using skb_network_offset(skb) + sizeof(struct iphdr/ipv6hdr) for\n  SKBMOD_F_ECN so that the required length is correctly calculated on\n  both ingress (offset == 0) and egress (offset == mac_len).\n- Setting max_edit_len to ETH_HLEN for Ethernet header modifications\n  after validating ARPHRD_ETHER.",
  "id": "CVE-2026-90078",
  "modified": "2026-09-19T03:31:01.498621891Z",
  "published": "2026-09-17T16:05:56.878Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0675cff3c2924eb9b80d9dd250cf56a1140af157"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1719865b20b22c88d2a55e922eff5ca31b0841f6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/62126464f3a6159c0a3dd89e196ba65bfeb0afc6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/81d0d1e64f30d9989c829c0953cd6e6c68d9c5fb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/985a37781ade19061400100c2ba0f43979dd4d63"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d896843d8d925f0adbba319020595cfb1a7bcd57"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e8a2027b7e686784a69b2dfcee841d779919f313"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/90xxx/CVE-2026-90078.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-90078"
    },
    {
      "type": "PACKAGE",
      "url": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
    }
  ],
  "schema_version": "1.9.0",
  "summary": "net/sched: act_skbmod: fix length calculations and avoid invalid header warnings"
}