Vulnerability-Lookup

GHSA-676R-CQGF-36VF

Vulnerability from github – Published: 2026-09-04 18:31 – Updated: 2026-09-04 18:31

Details

In the Linux kernel, the following vulnerability has been resolved:

batman-adv: reject unrepresentable multicast TVLV offsets

The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable.

If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32. batadv_mcast_forw_packet() consequently accepts an oversized multicast tracker and accesses memory beyond the skb data.

Add skb_set_transport_header_careful(), an offset-aware counterpart to skb_reset_transport_header_careful(), which validates the final head-relative offset before assigning it. Use the new helper in batadv_tvlv_call_handler() and reject unrepresentable TVLVs before setting the network header.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80839"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-09-04T16:18:12Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: reject unrepresentable multicast TVLV offsets\n\nThe network and transport header fields in struct sk_buff are 16-bit\noffsets from skb-\u003ehead, and U16_MAX is reserved as the unset transport\nheader value. batadv_tvlv_call_handler() sets both fields from a received\nmulticast TVLV without checking whether the TVLV end is representable.\n\nIf the end offset exceeds the field\u0027s range, skb_set_transport_header()\ntruncates it so that the transport header precedes the network header.\nThe negative difference is then returned by skb_network_header_len() as\na large u32. batadv_mcast_forw_packet() consequently accepts an oversized\nmulticast tracker and accesses memory beyond the skb data.\n\nAdd skb_set_transport_header_careful(), an offset-aware counterpart to\nskb_reset_transport_header_careful(), which validates the final\nhead-relative offset before assigning it. Use the new helper in\nbatadv_tvlv_call_handler() and reject unrepresentable TVLVs before\nsetting the network header.",
  "id": "GHSA-676r-cqgf-36vf",
  "modified": "2026-09-04T18:31:28Z",
  "published": "2026-09-04T18:31:28Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80839"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-80839 (GCVE-0-2026-80839)

Vulnerability from cvelistv5 – Published: 2026-09-04 15:54 – Updated: 2026-09-04 15:54

Title

batman-adv: reject unrepresentable multicast TVLV offsets

Summary

In the Linux kernel, the following vulnerability has been resolved: batman-adv: reject unrepresentable multicast TVLV offsets The network and transport header fields in struct sk_buff are 16-bit offsets from skb->head, and U16_MAX is reserved as the unset transport header value. batadv_tvlv_call_handler() sets both fields from a received multicast TVLV without checking whether the TVLV end is representable. If the end offset exceeds the field's range, skb_set_transport_header() truncates it so that the transport header precedes the network header. The negative difference is then returned by skb_network_header_len() as a large u32. batadv_mcast_forw_packet() consequently accepts an oversized multicast tracker and accesses memory beyond the skb data. Add skb_set_transport_header_careful(), an offset-aware counterpart to skb_reset_transport_header_careful(), which validates the final head-relative offset before assigning it. Use the new helper in batadv_tvlv_call_handler() and reject unrepresentable TVLVs before setting the network header.

Severity

No CVSS data available.

Assigner

Linux mitre root

References

5 references

URL	Tags
https://git.kernel.org/stable/c/da1f5aa7ec93f2cc1…
https://git.kernel.org/stable/c/916ec741e65af072b…
https://git.kernel.org/stable/c/1b466746fe109127f…
https://git.kernel.org/stable/c/2b46baa591d0a7c16…
https://git.kernel.org/stable/c/f12c2de4f542e3220…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2 (git) Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 916ec741e65af072b98e475feaad98c063da1b7c (git) Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 1b466746fe109127fd983100a228cdd1f1f6ece2 (git) Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 2b46baa591d0a7c16b62f150917187e70d053be6 (git) Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < f12c2de4f542e3220e17e0606f492110064f04cb (git)
Linux	Linux	Affected: 6.8 Unaffected: 0 , < 6.8 (semver) Unaffected: 6.12.108 , ≤ 6.12.* (semver) Unaffected: 6.18.49 , ≤ 6.18.* (semver) Unaffected: 7.1.13 , ≤ 7.1.* (semver) Unaffected: 7.2.3 , ≤ 7.2.* (semver) Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/skbuff.h",
            "net/batman-adv/tvlv.c"
          ],
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          "vendor": "Linux",
          "versions": [
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              "version": "07afe1ba288c04280622fa002ed385f1ac0b6fe6",
              "versionType": "git"
            },
            {
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              "status": "affected",
              "version": "07afe1ba288c04280622fa002ed385f1ac0b6fe6",
              "versionType": "git"
            },
            {
              "lessThan": "1b466746fe109127fd983100a228cdd1f1f6ece2",
              "status": "affected",
              "version": "07afe1ba288c04280622fa002ed385f1ac0b6fe6",
              "versionType": "git"
            },
            {
              "lessThan": "2b46baa591d0a7c16b62f150917187e70d053be6",
              "status": "affected",
              "version": "07afe1ba288c04280622fa002ed385f1ac0b6fe6",
              "versionType": "git"
            },
            {
              "lessThan": "f12c2de4f542e3220e17e0606f492110064f04cb",
              "status": "affected",
              "version": "07afe1ba288c04280622fa002ed385f1ac0b6fe6",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "include/linux/skbuff.h",
            "net/batman-adv/tvlv.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.8"
            },
            {
              "lessThan": "6.8",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.108",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.49",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.13",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.3",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
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                },
                {
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbatman-adv: reject unrepresentable multicast TVLV offsets\n\nThe network and transport header fields in struct sk_buff are 16-bit\noffsets from skb-\u003ehead, and U16_MAX is reserved as the unset transport\nheader value. batadv_tvlv_call_handler() sets both fields from a received\nmulticast TVLV without checking whether the TVLV end is representable.\n\nIf the end offset exceeds the field\u0027s range, skb_set_transport_header()\ntruncates it so that the transport header precedes the network header.\nThe negative difference is then returned by skb_network_header_len() as\na large u32. batadv_mcast_forw_packet() consequently accepts an oversized\nmulticast tracker and accesses memory beyond the skb data.\n\nAdd skb_set_transport_header_careful(), an offset-aware counterpart to\nskb_reset_transport_header_careful(), which validates the final\nhead-relative offset before assigning it. Use the new helper in\nbatadv_tvlv_call_handler() and reject unrepresentable TVLVs before\nsetting the network header."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-04T15:54:49.378Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
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          "url": "https://git.kernel.org/stable/c/da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2"
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          "url": "https://git.kernel.org/stable/c/916ec741e65af072b98e475feaad98c063da1b7c"
        },
        {
          "url": "https://git.kernel.org/stable/c/1b466746fe109127fd983100a228cdd1f1f6ece2"
        },
        {
          "url": "https://git.kernel.org/stable/c/2b46baa591d0a7c16b62f150917187e70d053be6"
        },
        {
          "url": "https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"
        }
      ],
      "title": "batman-adv: reject unrepresentable multicast TVLV offsets",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-80839",
    "datePublished": "2026-09-04T15:54:49.378Z",
    "dateReserved": "2026-08-26T14:34:25.796Z",
    "dateUpdated": "2026-09-04T15:54:49.378Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
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.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

GHSA-676R-CQGF-36VF

CVE-2026-80839 (GCVE-0-2026-80839)

Tags

Sightings

Nomenclature