CVE-2026-23139 (GCVE-0-2026-23139)

Vulnerability from cvelistv5 – Published: 2026-02-14 15:22 – Updated: 2026-08-05 12:20
VLAI
Title
netfilter: nf_conncount: update last_gc only when GC has been performed
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conncount: update last_gc only when GC has been performed Currently last_gc is being updated everytime a new connection is tracked, that means that it is updated even if a GC wasn't performed. With a sufficiently high packet rate, it is possible to always bypass the GC, causing the list to grow infinitely. Update the last_gc value only when a GC has been actually performed.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: f106694733c66a48740c25bc4e212e9b2ea364ce , < 2c7c71113ed6d3e2f3aca4c088f22283016ff34f (git)
Affected: be69850b461e7b491d87a22e33ab76fdd04b725e , < c4cde57c8affdcca5bcff53a1047e15d268bdca1 (git)
Affected: d265929930e2ffafc744c0ae05fb70acd53be1ee , < 9f45588993d7f115280fc726119ca86fba32a811 (git)
Affected: d265929930e2ffafc744c0ae05fb70acd53be1ee , < 3cd717359e56f82f06cbf8279b47a7d79880c6f3 (git)
Affected: d265929930e2ffafc744c0ae05fb70acd53be1ee , < 26a82dce2beee39c43c109d9647e16f49cb02a35 (git)
Affected: d265929930e2ffafc744c0ae05fb70acd53be1ee , < 8bdafdf4900040a81422056cabe5e00a37bd101a (git)
Affected: d265929930e2ffafc744c0ae05fb70acd53be1ee , < 7811ba452402d58628e68faedf38745b3d485e3c (git)
Create a notification for this product.
Linux Linux Affected: 5.19
Unaffected: 0 , < 5.19 (semver)
Unaffected: 6.1.161 , ≤ 6.1.* (semver)
Unaffected: 6.6.121 , ≤ 6.6.* (semver)
Unaffected: 6.12.66 , ≤ 6.12.* (semver)
Unaffected: 6.18.6 , ≤ 6.18.* (semver)
Unaffected: 6.19 , ≤ * (original_commit_for_fix)
Create a notification for this product.
Show details on NVD website
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{
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conncount: update last_gc only when GC has been performed\n\nCurrently last_gc is being updated everytime a new connection is\ntracked, that means that it is updated even if a GC wasn\u0027t performed.\nWith a sufficiently high packet rate, it is possible to always bypass\nthe GC, causing the list to grow infinitely.\n\nUpdate the last_gc value only when a GC has been actually performed."
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              "value": "AV:N - The vulnerability is triggered by network packets hitting connlimit rules (xt_connlimit, nft_connlimit) or OVS zone limits. A remote unauthenticated attacker can send a flood of packets to trigger the unbounded list growth.\nAC:L - The attacker fully controls the packet rate needed to bypass GC. The nf_conncount module is only loaded when connlimit is in use, so its deployment inherently implies connlimit rules exist. Exploitation is completely reliable.\nPR:N - No authentication or privileges are needed to send network packets that match connlimit rules. The attack is in the packet processing path, not the rule configuration path.\nUI:N - No user interaction is required. The attacker autonomously sends packets to trigger the vulnerability.\nS:U - The impact (kernel memory exhaustion) stays within the kernel\u0027s security boundary. No cross-boundary impact such as VM escape.\nC:N - This is a resource exhaustion bug where stale connections are never garbage collected. No information is disclosed to the attacker.\nI:N - No data modification or memory corruption occurs. The list simply grows unboundedly but the entries themselves are well-formed.\nA:H - The connection list grows infinitely, exhausting kernel slab memory via unbounded GFP_ATOMIC allocations. This leads to OOM conditions, system instability, and potential kernel panic."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:20:21.709Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23139",
    "datePublished": "2026-02-14T15:22:24.059Z",
    "dateReserved": "2026-01-13T15:37:45.972Z",
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Con una tasa de paquetes suficientemente alta, es posible eludir siempre la GC, haciendo que la lista crezca infinitamente.\\n\\nActualizar el valor de last_gc solo cuando se ha realizado realmente una 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-12T02:12:20+00:00",
      "cve": "CVE-2026-23139",
      "id": "CVE-2026-23139",
      "initial_release_date": "2026-02-14T00:00:00+00:00",
      "product_status:fixed": "307",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: nf_conncount: update last_gc only when GC has been performed",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23139.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-24T02:39:20Z",
      "cve": "CVE-2026-23139",
      "id": "CVE-2026-23139",
      "initial_release_date": "2026-02-18T00:25:20Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "450",
      "product_status:known_not_affected": "200",
      "product_status:recommended": "295",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-23139",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-23139.json",
      "version": "25"
    }
  }
}



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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.
  • 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.


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