net: openvswitch: validate transport header presence in set_ipv6_addr

{
  "id": "948e1ac0179a0213c1557f55e192c2ece7b34e29e333456928e358d56a402676",
  "url": "https://www.cve.org/CVERecord?id=CVE-2026-99088",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: openvswitch: validate transport header presence in set_ipv6_addr",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: validate transport header presence in set_ipv6_addr When executing IPv6 address rewrite actions on IPv6 fragments, set_ipv6_addr() calls update_ipv6_checksum(). If parse_ipv6hdr() processes a non-first IPv6 fragment, it sets key->ip.proto to NEXTHDR_FRAGMENT and returns early without calling skb_set_transport_header(). update_ipv6_checksum() unconditionally evaluates skb_transport_offset() on entry before checking l4_proto. Because skb->transport_header is uninitialized, this triggers a warning under CONFIG_DEBUG_NET=y although it is completely harmless. Fix this by returning early in update_ipv6_checksum() if l4_proto is NEXTHDR_FRAGMENT. This avoids reading the uninitialized transport offset for fragments while preserving the debug warning for any other protocol where the transport header is unexpectedly missing. See the syzbot trace: !skb_transport_header_was_set(skb) WARNING: ./include/linux/skbuff.h:3075 at skb_transport_header include/linux/skbuff.h:3075 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at skb_transport_offset include/linux/skbuff.h:3250 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at update_ipv6_checksum net/openvswitch/actions.c:361 [inline], CPU#1: syz-executor463/5635 WARNING: ./include/linux/skbuff.h:3075 at set_ipv6_addr+0x462/0x660 net/openvswitch/actions.c:399, CPU#1: syz-executor463/5635 [...] RIP: 001",
    "evidence": "cve:CVE-2026-99088",
    "products": [
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/0/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      },
      {
        "name": {
          "value": "Linux",
          "evidence": "/containers/cna/affected/1/product"
        },
        "prerequisites": [],
        "fixed_versions": [],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-99088",
      "aliases": [
        "CVE-2026-99088"
      ],
      "metrics": [],
      "affected": [
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b",
              "lessThan": "b7b80d204abdc258006f9e17c92b363ab13bb599",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b",
              "lessThan": "6774af7cd17be8f0d0f70de3a749d381b4f2e9da",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b",
              "lessThan": "2594795fd832f0253826d64ff8976b8ff5fbfe9f",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b",
              "lessThan": "6b8897ba0733f88f0360ea48a970f373f9142de0",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "3fdbd1ce11e5c0d7cafbe44c942c5cad61113d7b",
              "lessThan": "3c6a4b11330fe424557538a98fca9f0a4c5bf313",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/openvswitch/actions.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "3.8"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "3.8",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "6.6.160",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
            {
              "status": "unaffected",
              "version": "6.12.113",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.18.57",
              "versionType": "semver",
              "lessThanOrEqual": "6.18.*"
            },
            {
              "status": "unaffected",
              "version": "7.2.11",
              "versionType": "semver",
              "lessThanOrEqual": "7.2.*"
            },
            {
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/openvswitch/actions.c"
          ],
          "defaultStatus": "affected"
        }
      ],
      "modified": "2026-10-26T14:51:58.460Z",
      "provider": "cve",
      "references": [
        "https://git.kernel.org/stable/c/b7b80d204abdc258006f9e17c92b363ab13bb599",
        "https://git.kernel.org/stable/c/6774af7cd17be8f0d0f70de3a749d381b4f2e9da",
        "https://git.kernel.org/stable/c/2594795fd832f0253826d64ff8976b8ff5fbfe9f",
        "https://git.kernel.org/stable/c/6b8897ba0733f88f0360ea48a970f373f9142de0",
        "https://git.kernel.org/stable/c/3c6a4b11330fe424557538a98fca9f0a4c5bf313"
      ],
      "provider_metadata": {
        "cna": {
          "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
          "shortName": "Linux",
          "dateUpdated": "2026-10-26T14:51:58.460Z"
        }
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-99088",
        "evidence": "/cveMetadata/cveId"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-cve",
  "document_id": 311605,
  "published_at": "2026-10-26T14:51:58.46+00:00"
}