Vulnerability-Lookup

GHSA-R6MF-V83V-V392

Vulnerability from github – Published: 2026-08-15 06:32 – Updated: 2026-08-23 15:32

Details

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

net/sched: act_ct: preserve tc_skb_cb across defragmentation

tcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving and restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases the tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through act_ct therefore loses qdisc metadata such as pkt_segs and can trigger WARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.

Save and restore the full tc_skb_cb around nf_ct_handle_fragments(), matching the pattern used by ovs_ct_handle_fragments().

Severity

8.2 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

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{
  "affected": [],
  "aliases": [
    "CVE-2026-72057"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-15T06:21:15Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: preserve tc_skb_cb across defragmentation\n\ntcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving\nand restoring skb-\u003ecb. The defrag helper clears IPCB/IP6CB, which aliases\nthe tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through\nact_ct therefore loses qdisc metadata such as pkt_segs and can trigger\nWARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.\n\nSave and restore the full tc_skb_cb around nf_ct_handle_fragments(),\nmatching the pattern used by ovs_ct_handle_fragments().",
  "id": "GHSA-r6mf-v83v-v392",
  "modified": "2026-08-23T15:32:58Z",
  "published": "2026-08-15T06:32:10Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72057"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2400c4b05d58834b994500a9eec90a37db44187c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/67d6b00a54446c008f52cf70fc0c2ad0c712f85d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/9092e15defbe6c7bc241c306093ca9d358a578e7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b3d835407846134b0d54637c0281b39bebef831d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f7f45ceb855d9ba1cba594fb3f383255f7013fad"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/fb080b6f54835d5d4d11ce3122800e6f0f6689e6"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2026-72057 (GCVE-0-2026-72057)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:52 – Updated: 2026-08-23 12:46

Title

net/sched: act_ct: preserve tc_skb_cb across defragmentation

Summary

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: preserve tc_skb_cb across defragmentation tcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving and restoring skb->cb. The defrag helper clears IPCB/IP6CB, which aliases the tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through act_ct therefore loses qdisc metadata such as pkt_segs and can trigger WARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled. Save and restore the full tc_skb_cb around nf_ct_handle_fragments(), matching the pattern used by ovs_ct_handle_fragments().

Severity

8.2 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H

Assigner

Linux mitre root

References

7 references

URL	Tags
https://git.kernel.org/stable/c/fb080b6f54835d5d4…
https://git.kernel.org/stable/c/67d6b00a54446c008…
https://git.kernel.org/stable/c/2400c4b05d58834b9…
https://git.kernel.org/stable/c/5c3ae5f6c7c6de73e…
https://git.kernel.org/stable/c/b3d835407846134b0…
https://git.kernel.org/stable/c/f7f45ceb855d9ba1c…
https://git.kernel.org/stable/c/9092e15defbe6c7bc…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 0d76daf2013ce1da20eab5e26bd81d983e1c18fb , < fb080b6f54835d5d4d11ce3122800e6f0f6689e6 (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < 67d6b00a54446c008f52cf70fc0c2ad0c712f85d (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < 2400c4b05d58834b994500a9eec90a37db44187c (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < 5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < b3d835407846134b0d54637c0281b39bebef831d (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < f7f45ceb855d9ba1cba594fb3f383255f7013fad (git) Affected: ec624fe740b416fb68d536b37fb8eef46f90b5c2 , < 9092e15defbe6c7bc241c306093ca9d358a578e7 (git) Affected: 5.15.13 , < 5.15.217 (semver)
Linux	Linux	Affected: 5.16 Unaffected: 0 , < 5.16 (semver) Unaffected: 5.15.217 , ≤ 5.15.* (semver) Unaffected: 6.1.184 , ≤ 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)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/sched/act_ct.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "fb080b6f54835d5d4d11ce3122800e6f0f6689e6",
              "status": "affected",
              "version": "0d76daf2013ce1da20eab5e26bd81d983e1c18fb",
              "versionType": "git"
            },
            {
              "lessThan": "67d6b00a54446c008f52cf70fc0c2ad0c712f85d",
              "status": "affected",
              "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
              "versionType": "git"
            },
            {
              "lessThan": "2400c4b05d58834b994500a9eec90a37db44187c",
              "status": "affected",
              "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
              "versionType": "git"
            },
            {
              "lessThan": "5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac",
              "status": "affected",
              "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
              "versionType": "git"
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            {
              "lessThan": "b3d835407846134b0d54637c0281b39bebef831d",
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              "versionType": "git"
            },
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              "lessThan": "f7f45ceb855d9ba1cba594fb3f383255f7013fad",
              "status": "affected",
              "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
              "versionType": "git"
            },
            {
              "lessThan": "9092e15defbe6c7bc241c306093ca9d358a578e7",
              "status": "affected",
              "version": "ec624fe740b416fb68d536b37fb8eef46f90b5c2",
              "versionType": "git"
            },
            {
              "lessThan": "5.15.217",
              "status": "affected",
              "version": "5.15.13",
              "versionType": "semver"
            }
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          "product": "Linux",
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          ],
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          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.16"
            },
            {
              "lessThan": "5.16",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.217",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.184",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.145",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.97",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.5",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.217",
                  "versionStartIncluding": "5.15.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.184",
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                },
                {
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                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "5.16",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
                  "versionStartIncluding": "5.16",
                  "vulnerable": true
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                {
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: preserve tc_skb_cb across defragmentation\n\ntcf_ct_handle_fragments() calls nf_ct_handle_fragments() without saving\nand restoring skb-\u003ecb. The defrag helper clears IPCB/IP6CB, which aliases\nthe tc_skb_cb/qdisc_skb_cb control buffer. Fragmented traffic through\nact_ct therefore loses qdisc metadata such as pkt_segs and can trigger\nWARN_ON_ONCE() in qdisc_pkt_segs() when panic_on_warn is enabled.\n\nSave and restore the full tc_skb_cb around nf_ct_handle_fragments(),\nmatching the pattern used by ovs_ct_handle_fragments()."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.2,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug fires in tcf_ct_act() on the packet datapath (sch_handle_ingress/egress \u2192 tc_run \u2192 tcf_classify) when IP fragments arrive; on OVN/Kubernetes/SDN gateways and mlx5 offload nodes with act_ct already installed, a remote peer triggers it by sending fragmented traffic with no local access.\nAC:L - The attacker fully controls fragment boundaries and ordering; nf_ct_handle_fragments() memset of IPCB/IP6CB that aliases tc_skb_cb runs deterministically on each matching fragment through the configured ct action without races or memory-layout dependencies.\nPR:N - Installing act_ct requires CAP_NET_ADMIN, but triggering the bug on an already-configured internet-facing or tenant-facing gateway needs no target credentials; a remote attacker only sends crafted IP fragments, matching CNA precedent for packet-driven act_ct issues (e.g., CVE-2023-52610).\nUI:N - Exploitation requires only attacker-generated fragmented packets reaching a host with act_ct on clsact/ingress; no victim login, mount, or other interactive action is needed.\nS:U - WARN/panic and corrupted qdisc/tc metadata occur entirely within the host kernel security domain; this is not a VM escape, sandbox breakout, or IOMMU boundary bypass.\nC:N - memset(IPCB/IP6CB) zeroes tc_skb_cb/qdisc_skb_cb fields in place without out-of-bounds read or use-after-free; no kernel memory contents are disclosed to the attacker, only skb control-block metadata is clobbered.\nI:L - Clearing pkt_segs, pkt_len, post_ct, and zone corrupts tc/qdisc state consumed by bstats_update, sch_cake/sch_qfq, and cls_flower zone matching, enabling attacker-driven mis-accounting and mis-handling of packets on the affected path.\nA:H - Zeroed pkt_segs makes qdisc_pkt_segs() hit DEBUG_NET_WARN_ON_ONCE when it disagrees with GSO segment count; with panic_on_warn enabled this kernel-panics the host, and the condition is repeatable with sustained fragmented traffic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-23T12:46:36.427Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/fb080b6f54835d5d4d11ce3122800e6f0f6689e6"
        },
        {
          "url": "https://git.kernel.org/stable/c/67d6b00a54446c008f52cf70fc0c2ad0c712f85d"
        },
        {
          "url": "https://git.kernel.org/stable/c/2400c4b05d58834b994500a9eec90a37db44187c"
        },
        {
          "url": "https://git.kernel.org/stable/c/5c3ae5f6c7c6de73ea9b6a75154fe4ed343e1bac"
        },
        {
          "url": "https://git.kernel.org/stable/c/b3d835407846134b0d54637c0281b39bebef831d"
        },
        {
          "url": "https://git.kernel.org/stable/c/f7f45ceb855d9ba1cba594fb3f383255f7013fad"
        },
        {
          "url": "https://git.kernel.org/stable/c/9092e15defbe6c7bc241c306093ca9d358a578e7"
        }
      ],
      "title": "net/sched: act_ct: preserve tc_skb_cb across defragmentation",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72057",
    "datePublished": "2026-08-15T05:52:12.873Z",
    "dateReserved": "2026-08-09T03:40:39.903Z",
    "dateUpdated": "2026-08-23T12:46:36.427Z",
    "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-R6MF-V83V-V392

CVE-2026-72057 (GCVE-0-2026-72057)

Tags

Sightings

Nomenclature