CVE-2026-72338

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: net/sched: act_pedit: fix TOCTOU heap OOB write in tc offload There is a TOCTOU race condition in flower lockless approach between sizing a flow_rule buffer and filling it. [email protected] reports: The cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED (fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the independent locking domains make the race reachable in practice. KASAN confirms: BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930 Write of size 4 at addr ffff888001f27520 by task poc-toctou/312 The buggy address is located 0 bytes to the right of allocated 288-byte region [ffff888001f27400, ffff888001f27520) (cache kmalloc-512) Note: The result is a heap OOB write attacker-controlled content into the adjacent slab object (requires CAP_NET_ADMIN). The fix introduces reading tcfp_nkeys under act->tcfa_lock in all places using a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys(). Additionally we close the remaining TOCTOU window between the sizing read and the fill reads by more careful accounting. Rather than silently truncating the key count, which leads to incorrect action semantics offloaded to hardware and secondary OOB writes if the remaining capacity is zero or consumed by prior actions, we enforce remaining capacity checks and return -ENOSPC if the required space exceeds the remaining capacity.

Severity

HIGH

CVSS score

7.8 (v3.1)

Vulnerability status

Received

Source identifier

416baaa9-dc9f-4396-8d5f-8c081fb06d67

Published

2026-08-15 06:22:07.043000

Last modified

2026-10-30 13:19:49.890000

View original CVE JSON

{
  "id": "CVE-2026-72338",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2026-08-15T06:22:07.043",
  "lastModified": "2026-10-30T13:19:49.890",
  "vulnStatus": "Received",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_pedit: fix TOCTOU heap OOB write in tc offload\n\nThere is a TOCTOU race condition in flower lockless approach between sizing\na flow_rule buffer and filling it.\[email protected] reports:\nThe cls_flower classifier operates with TCF_PROTO_OPS_DOIT_UNLOCKED\n(fl_change runs without RTNL), while RTM_NEWACTION holds RTNL, so the\nindependent locking domains make the race reachable in practice.  KASAN\nconfirms:\n  BUG: KASAN: slab-out-of-bounds in tcf_pedit_offload_act_setup+0x81b/0x930\n  Write of size 4 at addr ffff888001f27520 by task poc-toctou/312\n  The buggy address is located 0 bytes to the right of\n   allocated 288-byte region [ffff888001f27400, ffff888001f27520)\n   (cache kmalloc-512)\n\nNote: The result is a heap OOB write attacker-controlled content into the\nadjacent slab object (requires CAP_NET_ADMIN).\n\nThe fix introduces reading tcfp_nkeys under act->tcfa_lock in all places\nusing a new tcf_pedit_nkeys_locked() which replaces the old tcf_pedit_nkeys().\nAdditionally we close the remaining TOCTOU window between the sizing read and\nthe fill reads by more careful accounting.\nRather than silently truncating the key count, which leads to incorrect\naction semantics offloaded to hardware and secondary OOB writes if\nthe remaining capacity is zero or consumed by prior actions, we enforce\nremaining capacity checks and return -ENOSPC if the required space exceeds\nthe remaining capacity."
    }
  ],
  "affected": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "affectedData": [
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "unaffected",
          "programFiles": [
            "include/net/tc_act/tc_pedit.h",
            "net/sched/act_api.c",
            "net/sched/act_pedit.c",
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
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              "lessThan": "1afdf2268b71251ea70d80bd8232a2f022e62a73",
              "versionType": "git",
              "status": "affected"
            },
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              "lessThan": "0d8532a5e972a5351cf4ee4a435e0d65cbba8f23",
              "versionType": "git",
              "status": "affected"
            },
            {
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              "lessThan": "27488e1a7f19757e6146edca9458ed4ffc545557",
              "versionType": "git",
              "status": "affected"
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            {
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              "versionType": "git",
              "status": "affected"
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              "versionType": "git",
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              "versionType": "git",
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            }
          ]
        },
        {
          "vendor": "Linux",
          "product": "Linux",
          "defaultStatus": "affected",
          "programFiles": [
            "include/net/tc_act/tc_pedit.h",
            "net/sched/act_api.c",
            "net/sched/act_pedit.c",
            "net/sched/cls_api.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "versions": [
            {
              "version": "4.11",
              "status": "affected"
            },
            {
              "version": "0",
              "lessThan": "4.11",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.1.191",
              "lessThanOrEqual": "6.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.6.145",
              "lessThanOrEqual": "6.6.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.12.97",
              "lessThanOrEqual": "6.12.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "6.18.40",
              "lessThanOrEqual": "6.18.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.1.5",
              "lessThanOrEqual": "7.1.*",
              "versionType": "semver",
              "status": "unaffected"
            },
            {
              "version": "7.2",
              "lessThanOrEqual": "*",
              "versionType": "original_commit_for_fix",
              "status": "unaffected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
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      {
        "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
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2026-10-16T18:47:17.190999Z",
          "id": "CVE-2026-72338",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "references": [
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      "url": "https://git.kernel.org/stable/c/0d8532a5e972a5351cf4ee4a435e0d65cbba8f23",
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}