CVE-2026-74668 (GCVE-0-2026-74668)

Vulnerability from cvelistv5 – Published: 2026-08-22 15:32 – Updated: 2026-08-27 12:40
VLAI
Title
packet: use consistent hard_header_len in TX_RING send path
Summary
In the Linux kernel, the following vulnerability has been resolved: packet: use consistent hard_header_len in TX_RING send path tpacket_snd() reads dev->hard_header_len independently for skb allocation and header construction in tpacket_fill_skb(). Concurrent netdevice reconfiguration can therefore make the reserved headroom smaller than the amount later pushed, or make copylen - hard_header_len negative. Snapshot hard_header_len once before processing ring frames and use it for the frame limit, headroom allocation, copy length, and skb construction. Pass the snapshot to tpacket_fill_skb(). The separate SOCK_DGRAM consistency problem between hard_header_len and header_ops->create is not addressed here.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < 9c7e8ff48c377bef18c3d178748aea0575b69ede (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < 2a73b2c37ee3060a880b53cd24783d93fc7be5f8 (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < e79f59a8527a49078cfaf8fe8fb5fcefc20c76d2 (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < d85d2fd54e901637c81d847811e03c662aee13cd (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < 016763e829cac37b3234eace86fd0a4c560de4a7 (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < 27e068d1b35dbec10a3cf268887c94407be4badc (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < d48ea5c9c4c34dc0df621f0e39ed3a16b644621a (git)
Affected: 69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1 , < 21b5953e7494c16a42e6cd8cf110e18d13ae4a6b (git)
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Linux Linux Affected: 2.6.31
Unaffected: 0 , < 2.6.31 (semver)
Unaffected: 5.10.267 , ≤ 5.10.* (semver)
Unaffected: 5.15.218 , ≤ 5.15.* (semver)
Unaffected: 6.1.185 , ≤ 6.1.* (semver)
Unaffected: 6.6.152 , ≤ 6.6.* (semver)
Unaffected: 6.12.104 , ≤ 6.12.* (semver)
Unaffected: 6.18.45 , ≤ 6.18.* (semver)
Unaffected: 7.1.9 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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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\npacket: use consistent hard_header_len in TX_RING send path\n\ntpacket_snd() reads dev-\u003ehard_header_len independently for skb\nallocation and header construction in tpacket_fill_skb(). Concurrent\nnetdevice reconfiguration can therefore make the reserved headroom\nsmaller than the amount later pushed, or make copylen - hard_header_len\nnegative.\n\nSnapshot hard_header_len once before processing ring frames and use it\nfor the frame limit, headroom allocation, copy length, and skb\nconstruction. Pass the snapshot to tpacket_fill_skb().\n\nThe separate SOCK_DGRAM consistency problem between hard_header_len and\nheader_ops-\u003ecreate is not addressed here."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The flaw is reached only via local syscalls on an AF_PACKET socket with PACKET_TX_RING configured (sendmsg on mmap ring frames); it is not triggered by processing remotely received network traffic.\nAC:L - An attacker can open the TX_RING socket and concurrently reconfigure the bound netdev (e.g., VLAN/bonding/macvlan changes) in a user+network namespace, controlling both sides of the hard_header_len race without depending on external timing.\nPR:L - Exploitation requires CAP_NET_RAW to create AF_PACKET sockets and CAP_NET_ADMIN to change netdev hard_header_len; both are obtainable by an unprivileged user inside a user namespace without init-namespace root.\nUI:N - No victim interaction is required; the attacker triggers the bug using their own packet socket, TX_RING, and netdev reconfiguration threads.\nS:U - Impact is kernel heap corruption and local privilege escalation within the same kernel security domain; it does not constitute a VM escape, sandbox breakout, or IOMMU boundary bypass.\nC:H - Racing hard_header_len can make skb_push exceed reserved headroom or skb_put use a negative length (huge unsigned), and subsequent skb_store_bits writes before skb-\u003ehead or far past skb-\u003etail, corrupting adjacent slab objects and enabling kernel memory disclosure.\nI:H - Inconsistent hard_header_len between skb allocation and tpacket_fill_skb causes out-of-bounds linear expansion and data writes in the skb buffer, yielding heap corruption primitives suitable for control-flow hijacking and local privilege escalation.\nA:H - Corrupted skb_push/put operations invoke skb_under_panic or skb_over_panic (BUG), causing kernel oops/panic and reliable denial of service even when exploitation is not completed."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-27T12:40:01.903Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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        {
          "url": "https://git.kernel.org/stable/c/9c7e8ff48c377bef18c3d178748aea0575b69ede"
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          "url": "https://git.kernel.org/stable/c/2a73b2c37ee3060a880b53cd24783d93fc7be5f8"
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      "title": "packet: use consistent hard_header_len in TX_RING send path",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74668",
    "datePublished": "2026-08-22T15:32:39.583Z",
    "dateReserved": "2026-08-15T05:44:03.924Z",
    "dateUpdated": "2026-08-27T12:40:01.903Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
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      "date": "2026-08-29",
      "epss": "0.00129",
      "percentile": "0.02876"
    },
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      "cve": "CVE-2026-74668",
      "id": "msrc_CVE-2026-74668",
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      "product_status:known_affected": "1",
      "source": "Microsoft CSAF VEX",
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      "title": "packet: use consistent hard_header_len in TX_RING send path",
      "url": "https://msrc.microsoft.com/csaf/vex/2026/msrc_cve-2026-74668.json",
      "version": "2"
    },
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Pass the snapshot to tpacket_fill_skb().\\n\\nThe separate SOCK_DGRAM consistency problem between hard_header_len and\\nheader_ops-\u003ecreate is not addressed here.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/packet/af_packet.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"9c7e8ff48c377bef18c3d178748aea0575b69ede\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"2a73b2c37ee3060a880b53cd24783d93fc7be5f8\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"e79f59a8527a49078cfaf8fe8fb5fcefc20c76d2\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"d85d2fd54e901637c81d847811e03c662aee13cd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"016763e829cac37b3234eace86fd0a4c560de4a7\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"27e068d1b35dbec10a3cf268887c94407be4badc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"d48ea5c9c4c34dc0df621f0e39ed3a16b644621a\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"69e3c75f4d541a6eb151b3ef91f34033cb3ad6e1\",\"lessThan\":\"21b5953e7494c16a42e6cd8cf110e18d13ae4a6b\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/packet/af_packet.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.31\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.31\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.267\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.218\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.185\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.152\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.104\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.45\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.9\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":5.9}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/016763e829cac37b3234eace86fd0a4c560de4a7\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/21b5953e7494c16a42e6cd8cf110e18d13ae4a6b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/27e068d1b35dbec10a3cf268887c94407be4badc\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/2a73b2c37ee3060a880b53cd24783d93fc7be5f8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9c7e8ff48c377bef18c3d178748aea0575b69ede\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d48ea5c9c4c34dc0df621f0e39ed3a16b644621a\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/d85d2fd54e901637c81d847811e03c662aee13cd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e79f59a8527a49078cfaf8fe8fb5fcefc20c76d2\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-25T08:53:53+00:00",
      "cve": "CVE-2026-74668",
      "id": "CVE-2026-74668",
      "initial_release_date": "2026-08-22T00:00:00+00:00",
      "product_status:known_affected": "274",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: packet: use consistent hard_header_len in TX_RING send path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74668.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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.
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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.


Detection rules are retrieved from Rulezet.