CVE-2026-98532 (GCVE-0-2026-98532)
Vulnerability from cvelistv5
Published
2026-10-18 15:17
Modified
2026-10-24 14:09
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv6: do not let ipv6_find_hdr() return an offset past the packet end ipv6_find_hdr() walks the extension header chain, skipping each header by the length that header itself declares. ipv6_optlen() returns up to 2048, and the skip is never checked against skb->len, so the offset stored in *offset can point past the end of the packet. openvswitch installs that offset as the transport header, and update_ipv6_checksum() then reads and writes the transport checksum field out of bounds: BUG: KASAN: slab-use-after-free in inet_proto_csum_replace16+0x445/0x470 Read of size 2 at addr ffff88810b754b06 by task ovs_ipv6_oob/629 CPU: 4 UID: 1000 PID: 629 Comm: ovs_ipv6_oob Tainted: G N 7.3.0-rc3+ #348 Call Trace: inet_proto_csum_replace16+0x445/0x470 set_ipv6_addr+0x3dd/0x460 do_execute_actions+0x6a3d/0x7c40 ovs_execute_actions+0xfd/0x480 ovs_packet_cmd_execute+0xc38/0xf20 genl_rcv_msg+0x59e/0x870 netlink_rcv_skb+0x18b/0x450 genl_rcv+0x2d/0x40 netlink_unicast+0x6bc/0xa20 The buggy address belongs to the object at ffff88810b754980 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 390 bytes inside of freed 704-byte region [ffff88810b754980, ffff88810b754c40) Other callers use that offset too, so bound it here rather than in one caller. Reject a header whose declared length does not fit in the packet. ipv6_find_hdr() already fails with -EBADMSG on a malformed chain, so this adds no new failure mode.
References
Impacted products
Vendor Product Version
Linux Linux Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
Version: f8f626754ebeca613cf1af2e6f890cfde0e74d5b
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{
  "containers": {
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        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/exthdrs_core.c"
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          "vendor": "Linux",
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
            }
          ]
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: do not let ipv6_find_hdr() return an offset past the packet end\n\nipv6_find_hdr() walks the extension header chain, skipping each header by\nthe length that header itself declares.  ipv6_optlen() returns up to 2048,\nand the skip is never checked against skb-\u003elen, so the offset stored in\n*offset can point past the end of the packet.\n\nopenvswitch installs that offset as the transport header, and\nupdate_ipv6_checksum() then reads and writes the transport checksum field\nout of bounds:\n\n  BUG: KASAN: slab-use-after-free in inet_proto_csum_replace16+0x445/0x470\n  Read of size 2 at addr ffff88810b754b06 by task ovs_ipv6_oob/629\n  CPU: 4 UID: 1000 PID: 629 Comm: ovs_ipv6_oob Tainted: G N 7.3.0-rc3+ #348\n  Call Trace:\n   inet_proto_csum_replace16+0x445/0x470\n   set_ipv6_addr+0x3dd/0x460\n   do_execute_actions+0x6a3d/0x7c40\n   ovs_execute_actions+0xfd/0x480\n   ovs_packet_cmd_execute+0xc38/0xf20\n   genl_rcv_msg+0x59e/0x870\n   netlink_rcv_skb+0x18b/0x450\n   genl_rcv+0x2d/0x40\n   netlink_unicast+0x6bc/0xa20\n\n  The buggy address belongs to the object at ffff88810b754980\n   which belongs to the cache skbuff_small_head of size 704\n  The buggy address is located 390 bytes inside of\n   freed 704-byte region [ffff88810b754980, ffff88810b754c40)\n\nOther callers use that offset too, so bound it here rather than in one\ncaller.\n\nReject a header whose declared length does not fit in the packet.\nipv6_find_hdr() already fails with -EBADMSG on a malformed chain, so this\nadds no new failure mode."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - A routed IPv6 datagram can carry a short Destination Options header whose hdrlen declares up to 2048 bytes; __netif_receive_skb_core() -\u003e netdev_frame_hook() -\u003e ovs_vport_receive() -\u003e parse_ipv6hdr() reaches the patched ipv6_find_hdr(), which returns a transport offset beyond skb-\u003elen.\nAC:H - Corruption requires the packet to match a preinstalled OVS_ACTION_ATTR_SET_MASKED IPv6 address-rewrite action that changes an address; although the sender controls nexthdr and hdrlen, that capability-gated datapath state is outside a remote attacker\u0027s control.\nPR:N - netdev_frame_hook() and ovs_vport_receive() process matching received packets without authentication or capability checks; GENL_UNS_ADMIN_PERM protects installation of the OVS flow, not the remote sender triggering it.\nUI:N - Once the affected OVS rewrite flow exists, packet receipt automatically runs parse_ipv6hdr(), ovs_dp_process_packet(), and set_ipv6_addr() without any victim action.\nS:U - The bad offset from ipv6_find_hdr() and the resulting skbuff corruption occur within the same host kernel networking security authority; this is ordinary in-kernel compromise rather than a boundary-enforcement bypass.\nC:H - inet_proto_csum_replace16() reads the attacker-selected out-of-range 16-bit location before rewriting it; hdrlen can place this access in adjacent or reclaimed skbuff_small_head storage, where corrupting skb pointer or length metadata can enable broader kernel-memory disclosure.\nI:H - inet_proto_csum_replace16() stores through tcp_hdr(), udp_hdr(), or icmp6_hdr() at the unchecked transport offset; hdrlen selects a location up to roughly 2 KiB past the packet and the IPv6 address delta controls the 16-bit modification, yielding an exploitable heap-write primitive.\nA:H - The demonstrated set_ipv6_addr() path produced a KASAN slab-use-after-free in inet_proto_csum_replace16(); repeated matching packets can corrupt adjacent skb storage and cause a kernel oops or panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-24T14:09:19.064Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/ca96b38730e31357ef4a9d76af1336958ac670d7"
        },
        {
          "url": "https://git.kernel.org/stable/c/531255de8971c06d5d5986f85fdc2525d707ba71"
        },
        {
          "url": "https://git.kernel.org/stable/c/543354c6efb27eae3372a3a9674aeaa2a86e2b2c"
        },
        {
          "url": "https://git.kernel.org/stable/c/dc92cb972e86790b8078337ec41015b748b8f8e5"
        },
        {
          "url": "https://git.kernel.org/stable/c/1c70275ca87e769e1a52abc644d61372d8c016cb"
        },
        {
          "url": "https://git.kernel.org/stable/c/1d42828565889632068fbc2983c34d57c66af4e0"
        },
        {
          "url": "https://git.kernel.org/stable/c/4254d5878c320c19961dd0b8e1d0aca4800d8b7d"
        },
        {
          "url": "https://git.kernel.org/stable/c/ee319bd3a0e976af5087cbe59ebc50a66f31d202"
        }
      ],
      "title": "ipv6: do not let ipv6_find_hdr() return an offset past the packet end",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98532",
    "datePublished": "2026-10-18T15:17:50.490Z",
    "dateReserved": "2026-09-25T10:25:14.355Z",
    "dateUpdated": "2026-10-24T14:09:19.064Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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