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CVE-2026-72351 (GCVE-0-2026-72351)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:55 – Updated: 2026-08-17 05:43
VLAI
Title
gue: validate REMCSUM private option length
Summary
In the Linux kernel, the following vulnerability has been resolved: gue: validate REMCSUM private option length GUE private flags can indicate that remote checksum offload metadata is present. The private flags field itself is accounted for by guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even when GUE_PFLAG_REMCSUM is set. This lets a packet with only the private flags field pass validate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum() read the missing REMCSUM start/offset fields from the following bytes. Account for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that malformed packets are rejected during option validation.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 158b9995d3c87f3b93f5c22df54a12e12a3438b3 (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 7c6876ec1b227261b51803f784c7be1b2242a1a0 (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 2c4de9988e9ddc760b750d6b6e701c35ff60ad14 (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 2a99224c120823987e4d829726f4ecb33e03fc1e (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 61e78679c7c9ca685bff58e4b6348304dc60aafd (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < 4a4a1d41c6e901e773bcf795f562a47fa71f692a (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < f618cbe9b24cd0202004d2db781d5f80ab77037f (git)
Affected: c1aa8347e73e4092411fbd96cc59531fb7e76d04 , < d335dcc6f521571d57117b8deeebc940836e5450 (git)
guessed Create a notification for this product.
Linux Linux Affected: 3.19
Unaffected: 0 , < 3.19 (semver)
Unaffected: 5.10.261 , ≤ 5.10.* (semver)
Unaffected: 5.15.212 , ≤ 5.15.* (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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                  "versionStartIncluding": "3.19",
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ngue: validate REMCSUM private option length\n\nGUE private flags can indicate that remote checksum offload metadata is\npresent. The private flags field itself is accounted for by\nguehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even\nwhen GUE_PFLAG_REMCSUM is set.\n\nThis lets a packet with only the private flags field pass\nvalidate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum()\nread the missing REMCSUM start/offset fields from the following bytes.\n\nAccount for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that\nmalformed packets are rejected during option validation."
        }
      ],
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            "version": "3.1"
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              "value": "AV:N - Malformed GUE-over-UDP packets reach gue_udp_recv() and gue_gro_receive() through the normal IP/UDP receive path on hosts with FOU/GUE listeners, including internet-facing cloud overlay endpoints.\nAC:L - An attacker fully controls the crafted packet and can set GUE_PFLAG_REMCSUM with only the private-flags option present, reliably triggering gue_remcsum()/gue_gro_remcsum() without races or special timing.\nPR:N - Exploitation requires only sending UDP to a GUE listener port; no target credentials or local privileges are needed by the remote attacker even though tunnel setup itself requires admin configuration.\nUI:N - No victim interaction is required beyond the host already receiving GUE tunnel traffic as part of normal overlay networking operation.\nS:U - The flaw corrupts kernel packet buffers during GUE receive processing on the target host and does not inherently cross VM, container, or IOMMU security boundaries.\nC:H - Missing REMCSUM length validation lets attacker-controlled start/offset drive remcsum_adjust()/csum_partial() to read beyond the declared GUE options into adjacent skb bytes, enabling memory disclosure primitives.\nI:H - remcsum_adjust() performs an out-of-bounds 2-byte write at ptr+offset, and the default partial-checksum path stores attacker-controlled csum_start/csum_offset metadata that can corrupt subsequent checksum offload handling.\nA:H - Out-of-bounds REMCSUM processing can trigger kernel oops or panic from invalid memory access or corrupted packet state, causing denial of service on overlay endpoints under repeated attack."
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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      "title": "gue: validate REMCSUM private option length",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72351",
    "datePublished": "2026-08-15T05:55:54.150Z",
    "dateReserved": "2026-08-09T03:40:39.921Z",
    "dateUpdated": "2026-08-17T05:43:08.849Z",
    "state": "PUBLISHED"
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The private flags field itself is accounted for by\\nguehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even\\nwhen GUE_PFLAG_REMCSUM is set.\\n\\nThis lets a packet with only the private flags field pass\\nvalidate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum()\\nread the missing REMCSUM start/offset fields from the following bytes.\\n\\nAccount for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that\\nmalformed packets are rejected during option 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T17:54:46+00:00",
      "cve": "CVE-2026-72351",
      "id": "CVE-2026-72351",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_not_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: gue: validate REMCSUM private option length",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72351.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-15T01:26:41Z",
      "cve": "CVE-2026-72351",
      "id": "CVE-2026-72351",
      "initial_release_date": "2026-08-22T00:53:55Z",
      "product_status:known_affected": "358",
      "product_status:known_not_affected": "4",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-72351",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-72351.json",
      "version": "5"
    }
  }
}



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