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

Vulnerability from cvelistv5 – Published: 2026-09-04 15:54 – Updated: 2026-10-19 08:44
VLAI
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 CNA under the mitre root
CNA scorecard D 53/100 over 6641 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < da1f5aa7ec93f2cc17f5cd30efc54f62af433cf2 (git)
Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 916ec741e65af072b98e475feaad98c063da1b7c (git)
Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 1b466746fe109127fd983100a228cdd1f1f6ece2 (git)
Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < 2b46baa591d0a7c16b62f150917187e70d053be6 (git)
Affected: 07afe1ba288c04280622fa002ed385f1ac0b6fe6 , < f12c2de4f542e3220e17e0606f492110064f04cb (git)
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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 , ≤ * (original_commit_for_fix)
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "include/linux/skbuff.h",
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          "vendor": "Linux",
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          "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": {
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        },
        {
          "url": "https://git.kernel.org/stable/c/f12c2de4f542e3220e17e0606f492110064f04cb"
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      "title": "batman-adv: reject unrepresentable multicast TVLV offsets",
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    "cveId": "CVE-2026-80839",
    "datePublished": "2026-09-04T15:54:49.378Z",
    "dateReserved": "2026-08-26T14:34:25.796Z",
    "dateUpdated": "2026-10-19T08:44:32.478Z",
    "state": "PUBLISHED"
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        "descriptions": [
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            "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."
          }
        ],
        "id": "CVE-2026-80839",
        "lastModified": "2026-10-19T09:17:19.223",
        "metrics": {},
        "published": "2026-09-04T16:18:12.310",
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      "current_release_date": "2026-11-07T10:36:47+00:00",
      "cve": "CVE-2026-80839",
      "id": "CVE-2026-80839",
      "initial_release_date": "2026-09-04T00:00:00+00:00",
      "product_status:known_not_affected": "203",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: batman-adv: reject unrepresentable multicast TVLV offsets",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-80839.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-11-12T01:15:07Z",
      "cve": "CVE-2026-80839",
      "id": "CVE-2026-80839",
      "initial_release_date": "2026-09-05T00:26:25Z",
      "product_status:known_affected": "2",
      "product_status:known_not_affected": "354",
      "product_status:recommended": "73",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-80839",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/2026/cve-2026-80839.json",
      "version": "7"
    }
  }
}



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