CVE-2026-74746 (GCVE-0-2026-74746)

Vulnerability from cvelistv5 – Published: 2026-08-26 14:36 – Updated: 2026-08-27 05:01
VLAI
Title
netfilter: flowtable: publish GC-visible tuple last
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: flowtable: publish GC-visible tuple last nf_flow_table_iterate() only treats original-direction tuple nodes as owning entries. Publishing the original node first lets GC observe and free a flow while flow_offload_add() is still inserting the reply node. Publish the reply node first and the original node last so GC never sees a partially installed flow. KASAN can trigger slab-use-after-free read and write reports in the flowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del, flow_offload_lookup, etc.).
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
Linux CNA under the mitre root
CNA scorecard D 54/100 over 6633 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < 0a00254585827f1695aa2700114af622ea754cfa (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < be345dcbddb4643a54252b954af974b16eda8f91 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < 211ee5d998d92a7d548811939c65942d06c146e4 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < d37917e7bebe078f3c17e47fd6fc1c9f6e8497b2 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < 972fdf7c4f5c282a239c88fea614b056c33dc025 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < d9d3050a70efe217e73a0751e55fdae6a7092620 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < d16b71231e65cb05daea2b45701fcf09cef041e7 (git)
Affected: ac2a66665e231847cab11b8c8e844ce43207dd2e , < 2014ac62df9d45bb9a004a043e85df7be09ed780 (git)
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Linux Linux Affected: 4.16
Unaffected: 0 , < 4.16 (semver)
Unaffected: 5.10.266 , ≤ 5.10.* (semver)
Unaffected: 5.15.217 , ≤ 5.15.* (semver)
Unaffected: 6.1.184 , ≤ 6.1.* (semver)
Unaffected: 6.6.153 , ≤ 6.6.* (semver)
Unaffected: 6.12.105 , ≤ 6.12.* (semver)
Unaffected: 6.18.46 , ≤ 6.18.* (semver)
Unaffected: 7.1.10 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
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              "value": "AV:N - flow_offload_add runs from nft_flow_offload_eval on the FORWARD hook and from tc act_ct during softirq packet processing when remote TCP/UDP traffic creates new offloaded conntrack flows on nftables flowtable routers/gateways, not through netlink configuration APIs.\nAC:L - The attacker controls when flows are offloaded (packet rate/timing) and can race connection teardown so nf_flow_table_gc_run observes a partially installed original tuple while reply insertion is still in progress; both the insert and GC sides of the race are attacker-driven.\nPR:N - On the intended edge-router/OpenWrt deployment, nftables flow offload is an administrator prerequisite; a remote sender needs no local account, authentication, or CAP_NET_ADMIN on the victim to trigger flow_offload_add while forwarding traffic.\nUI:N - Exploitation requires only sending network packets processed automatically on the forwarding or ingress path; no victim must open files, mount filesystems, or take any interactive action beyond normal traffic through the router.\nS:U - Slab use-after-free in the flowtable rhashtable/GC path affects only in-kernel memory on the affected host; this is standard kernel compromise within one security authority, not a VM escape, IOMMU bypass, or cross-boundary sandbox break.\nC:H - The fix commit documents KASAN slab-use-after-free read and write reports in rht_deferred_worker, jhash, flow_offload_del, and flow_offload_lookup; UAF on flow_offload kmem-cache objects enables arbitrary kernel memory disclosure via heap grooming.\nI:H - Freed flow_offload structures remain reachable during concurrent rhashtable insert/remove and deferred worker operations, providing attacker-influenceable heap corruption that can be groomed into arbitrary kernel writes and control-flow hijack.\nA:H - Concurrent GC freeing of a partially inserted flow while flow_offload_add or rhashtable workers still access it causes kernel oops/panic and reliable denial of service; UAF on the flow offload path can crash forwarding routers under sustained malicious traffic."
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            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: flowtable: publish GC-visible tuple last\n\nnf_flow_table_iterate() only treats original-direction tuple nodes as\nowning entries. Publishing the original node first lets GC observe and\nfree a flow while flow_offload_add() is still inserting the reply node.\nPublish the reply node first and the original node last so GC never\nsees a partially installed flow.\n\nKASAN can trigger slab-use-after-free read and write reports in the\nflowtable/rhashtable path (rht_deferred_worker, jhash, flow_offload_del,\nflow_offload_lookup, etc.)."
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        "metrics": {
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                "attackVector": "NETWORK",
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                "baseScore": 9.8,
                "baseSeverity": "CRITICAL",
                "confidentialityImpact": "HIGH",
                "integrityImpact": "HIGH",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
                "version": "3.1"
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              "impactScore": 5.9,
              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
            }
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        "published": "2026-08-26T15:16:53.503",
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        "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "vulnStatus": "Received"
      }
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    "redhat_vex": {
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      "current_release_date": "2026-10-08T21:17:21+00:00",
      "cve": "CVE-2026-74746",
      "id": "CVE-2026-74746",
      "initial_release_date": "2026-08-26T00:00:00+00:00",
      "product_status:fixed": "1813",
      "product_status:known_affected": "99",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: flowtable: publish GC-visible tuple last",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74746.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-09-15T01:15:18Z",
      "cve": "CVE-2026-74746",
      "id": "CVE-2026-74746",
      "initial_release_date": "2026-09-02T11:43:21Z",
      "product_status:known_affected": "260",
      "product_status:known_not_affected": "93",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-74746",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-74746.json",
      "version": "5"
    }
  }
}



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Taxonomy of the tags.





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

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.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.