CVE-2026-98570 (GCVE-0-2026-98570)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:18 – Updated: 2026-10-19 09:21
VLAI
Title
net: ipv6: keep room for the mac header in dst_dev_overhead()
Summary
In the Linux kernel, the following vulnerability has been resolved: net: ipv6: keep room for the mac header in dst_dev_overhead() The seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as the length they are about to push plus dst_dev_overhead(), then push the new headers and rebuild the mac header below them with skb_mac_header_rebuild(). That rebuild needs skb->mac_len of headroom, but dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device, 16 bytes for plain Ethernet. Where the mac header is longer than that, as it is on ingress through a VLAN device with reorder_hdr off, the rebuild runs out of room: skb_set_mac_header(skb, -skb->mac_len) computes a negative offset, stores it unchecked in the u16 skb->mac_header, and the memmove that follows writes skb->mac_len bytes about 64 KB past skb->head. Forwarding plain ping6 traffic through such a device reproduces it on all five seg6 encapsulation modes and on the rpl and ioam6 inline paths; skb->mac_header comes back as 65534 on a 704-byte head. Return the larger of the two. The helper already returns skb->mac_len when it has no dst, so this only makes the other branch agree, and it covers every caller rather than each call site in turn.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6820 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: dce525185bc92864e5a318040285ee070563fe34 , < 36c07127924f11fc5741a780abcaaf808fe9ef13 (git)
Affected: dce525185bc92864e5a318040285ee070563fe34 , < 87cd6b717e4069dca34e0866e57eaeb44d3b173e (git)
Affected: 8471e228448a818e4c27cab4b681b2e758e46cf5 (git)
Affected: c432cd18a07b623651ed15ea167bd303467004cc (git)
Affected: 634710a372ba65bee667c2f6e58a97658c639eab (git)
Affected: c447c5a9c47bb4858ab12bf90879fe595d2b7f46 (git)
Affected: ab9de9c48316d2622d3bf353916b99971570e2c9 (git)
Affected: 2fcc9f3798ef82399564d247458e69abd10e683b (git)
Affected: 371d8dc298b4f59e99b4564ac5d906fce0932c69 (git)
Affected: b26f015dfb07b6be12d005a0ed0c5c43b7bedbf3 (git)
Affected: c0b11dc50590e10590b39dcda79835cd32f49d00 (git)
Affected: 4c12c3c8abd8b888945d31e7bdbb0d8b73032fc5 (git)
Affected: 25d8e065c7972dc98fd7a4cac322d5367eaede88 (git)
Affected: 4a855c5aec41bf84922224ab7a74e088776e3ac4 (git)
Affected: a9f0407414e16176fdbbbd298c9e18d6dfdf96bc (git)
Affected: 6.12.16 , < 6.13 (semver)
Affected: 6.13.4 , < 6.14 (semver)
Affected: 5.15.179 , < 5.16 (semver)
Affected: 6.1.130 , < 6.2 (semver)
Affected: 6.6.81 , < 6.7 (semver)
Affected: 5.10.235 , < 5.11 (semver)
guessed Create a notification for this product.
Linux Linux Affected: 6.14
Unaffected: 0 , < 6.14 (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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{
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: keep room for the mac header in dst_dev_overhead()\n\nThe seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as\nthe length they are about to push plus dst_dev_overhead(), then push the\nnew headers and rebuild the mac header below them with\nskb_mac_header_rebuild().  That rebuild needs skb-\u003emac_len of headroom,\nbut dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device,\n16 bytes for plain Ethernet.\n\nWhere the mac header is longer than that, as it is on ingress through a\nVLAN device with reorder_hdr off, the rebuild runs out of room:\nskb_set_mac_header(skb, -skb-\u003emac_len) computes a negative offset,\nstores it unchecked in the u16 skb-\u003emac_header, and the memmove that\nfollows writes skb-\u003emac_len bytes about 64 KB past skb-\u003ehead.\nForwarding plain ping6 traffic through such a device reproduces it on\nall five seg6 encapsulation modes and on the rpl and ioam6 inline paths;\nskb-\u003emac_header comes back as 65534 on a 704-byte head.\n\nReturn the larger of the two.  The helper already returns skb-\u003emac_len\nwhen it has no dst, so this only makes the other branch agree, and it\ncovers every caller rather than each call site in turn."
        }
      ],
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        "dateUpdated": "2026-10-19T09:21:55.765Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13"
        },
        {
          "url": "https://git.kernel.org/stable/c/87cd6b717e4069dca34e0866e57eaeb44d3b173e"
        }
      ],
      "title": "net: ipv6: keep room for the mac header in dst_dev_overhead()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98570",
    "datePublished": "2026-10-18T15:18:36.308Z",
    "dateReserved": "2026-09-25T10:25:14.357Z",
    "dateUpdated": "2026-10-19T09:21:55.765Z",
    "state": "PUBLISHED"
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  "dataVersion": "5.2",
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    "epss": {
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      "date": "2026-11-02",
      "epss": "0.00189",
      "percentile": "0.08575"
    },
    "microsoft_vex": {
      "current_release_date": "2026-10-24T14:47:20.000Z",
      "cve": "CVE-2026-98570",
      "id": "msrc_CVE-2026-98570",
      "initial_release_date": "2026-10-20T01:09:04.000Z",
      "product_status:fixed": "1",
      "product_status:known_affected": "1",
      "product_status:under_investigation": "1",
      "source": "Microsoft CSAF VEX",
      "status": "final",
      "title": "net: ipv6: keep room for the mac header in dst_dev_overhead()",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-98570.json",
      "version": "3"
    },
    "nvd": {
      "cve": {
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        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: keep room for the mac header in dst_dev_overhead()\n\nThe seg6, ioam6 and rpl lwtunnels size their skb_cow_head() request as\nthe length they are about to push plus dst_dev_overhead(), then push the\nnew headers and rebuild the mac header below them with\nskb_mac_header_rebuild().  That rebuild needs skb-\u003emac_len of headroom,\nbut dst_dev_overhead() leaves LL_RESERVED_SPACE() of the egress device,\n16 bytes for plain Ethernet.\n\nWhere the mac header is longer than that, as it is on ingress through a\nVLAN device with reorder_hdr off, the rebuild runs out of room:\nskb_set_mac_header(skb, -skb-\u003emac_len) computes a negative offset,\nstores it unchecked in the u16 skb-\u003emac_header, and the memmove that\nfollows writes skb-\u003emac_len bytes about 64 KB past skb-\u003ehead.\nForwarding plain ping6 traffic through such a device reproduces it on\nall five seg6 encapsulation modes and on the rpl and ioam6 inline paths;\nskb-\u003emac_header comes back as 65534 on a 704-byte head.\n\nReturn the larger of the two.  The helper already returns skb-\u003emac_len\nwhen it has no dst, so this only makes the other branch agree, and it\ncovers every caller rather than each call site in turn."
          }
        ],
        "id": "CVE-2026-98570",
        "lastModified": "2026-10-19T10:19:15.053",
        "metrics": {},
        "published": "2026-10-18T16:17:09.233",
        "references": [
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/36c07127924f11fc5741a780abcaaf808fe9ef13"
          },
          {
            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "url": "https://git.kernel.org/stable/c/87cd6b717e4069dca34e0866e57eaeb44d3b173e"
          }
        ],
        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-20T03:08:33+00:00",
      "cve": "CVE-2026-98570",
      "id": "CVE-2026-98570",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_not_affected": "277",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: ipv6: keep room for the mac header in dst_dev_overhead()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98570.json",
      "version": "3"
    }
  }
}



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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

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    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.