CVE-2026-98622 (GCVE-0-2026-98622)

Vulnerability from cvelistv5 – Published: 2026-10-18 15:19 – Updated: 2026-10-19 09:22
VLAI
Title
net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure
Summary
In the Linux kernel, the following vulnerability has been resolved: net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure flow_offload_alloc() returns NULL when the conntrack entry is dying (e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation fails; both are expected under load and neither is a kernel bug. This path runs from softirq on every committed packet, so with panic_on_warn=1 an unprivileged user can panic the box just by racing a conntrack flush against a `tc ... action ct commit` classifier. Reproduced with a custom repro under QEMU: a small, fixed set of UDP flows through `tc filter ... action ct commit` on lo, raced against threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined into tcf_ct_act() in this build) within ~15s on the unpatched kernel; same setup is clean on the patched kernel. The fix itself is behavior-preserving: both branches already did `goto err_alloc` before and after, only the WARN is removed.
Severity
No CVSS data available.
Assigner
Linux CNA under the mitre root
CNA scorecard D 53/100 over 6794 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < e8fcf3f08834e939b797311742ee72b1e2a08096 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < af475f599270e59313552e6c6f3af8507da672b8 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < 424ba52c0058deeb940d02cba52eb0aeb288db33 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < d805560ad69cb266d669341ca01e26bffb0d2c67 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < 00734f3684fcec42c319bedfe68a5d357c720b53 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < 650787233c2fd6e515a7c5f371019a9fa080ccd2 (git)
Affected: 64ff70b80fd403110b67dd9f7184a604fdb0da43 , < 47abe7a5c4eb53269aca3506446f851572a059a3 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 5.10.271 , ≤ 5.10.* (semver)
Unaffected: 5.15.222 , ≤ 5.15.* (semver)
Unaffected: 6.1.189 , ≤ 6.1.* (semver)
Unaffected: 6.6.158 , ≤ 6.6.* (semver)
Unaffected: 6.12.112 , ≤ 6.12.* (semver)
Unaffected: 6.18.55 , ≤ 6.18.* (semver)
Unaffected: 7.2.9 , ≤ 7.2.* (semver)
Unaffected: 7.3 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure\n\nflow_offload_alloc() returns NULL when the conntrack entry is dying\n(e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation\nfails; both are expected under load and neither is a kernel bug. This\npath runs from softirq on every committed packet, so with\npanic_on_warn=1 an unprivileged user can panic the box just by racing\na conntrack flush against a `tc ... action ct commit` classifier.\n\nReproduced with a custom repro under QEMU: a small, fixed set of UDP\nflows through `tc filter ... action ct commit` on lo, raced against\nthreads flooding bare ctnetlink CT_DELETE (flush) requests. Hits\nWARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined\ninto tcf_ct_act() in this build) within ~15s on the unpatched kernel;\nsame setup is clean on the patched kernel. The fix itself is\nbehavior-preserving: both branches already did `goto err_alloc`\nbefore and after, only the WARN is removed."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-19T09:22:50.359Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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      "title": "net/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure",
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    "cveId": "CVE-2026-98622",
    "datePublished": "2026-10-18T15:19:42.514Z",
    "dateReserved": "2026-09-25T10:25:14.360Z",
    "dateUpdated": "2026-10-19T09:22:50.359Z",
    "state": "PUBLISHED"
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      "source": "Microsoft CSAF VEX",
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      "title": "net/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure",
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure\n\nflow_offload_alloc() returns NULL when the conntrack entry is dying\n(e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation\nfails; both are expected under load and neither is a kernel bug. This\npath runs from softirq on every committed packet, so with\npanic_on_warn=1 an unprivileged user can panic the box just by racing\na conntrack flush against a `tc ... action ct commit` classifier.\n\nReproduced with a custom repro under QEMU: a small, fixed set of UDP\nflows through `tc filter ... action ct commit` on lo, raced against\nthreads flooding bare ctnetlink CT_DELETE (flush) requests. Hits\nWARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined\ninto tcf_ct_act() in this build) within ~15s on the unpatched kernel;\nsame setup is clean on the patched kernel. The fix itself is\nbehavior-preserving: both branches already did `goto err_alloc`\nbefore and after, only the WARN is removed."
          }
        ],
        "id": "CVE-2026-98622",
        "lastModified": "2026-10-19T10:19:26.330",
        "metrics": {},
        "published": "2026-10-18T16:17:15.117",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-10-30T07:03:48+00:00",
      "cve": "CVE-2026-98622",
      "id": "CVE-2026-98622",
      "initial_release_date": "2026-10-18T00:00:00+00:00",
      "product_status:known_affected": "237",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net/sched: act_ct: don\u0027t WARN on benign flow_offload_alloc() failure",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-98622.json",
      "version": "3"
    }
  }
}



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