CVE-2026-23139 (GCVE-0-2026-23139)
Vulnerability from cvelistv5 – Published: 2026-02-14 15:22 – Updated: 2026-08-05 12:20
VLAI
EPSS
VEX
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)
Assigner
References
7 references
Impacted products
2 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| 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) |
guessed | |
| 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) |
guessed |
{
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},
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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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"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"scenarios": [
{
"lang": "en",
"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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},
{
"url": "https://git.kernel.org/stable/c/c4cde57c8affdcca5bcff53a1047e15d268bdca1"
},
{
"url": "https://git.kernel.org/stable/c/9f45588993d7f115280fc726119ca86fba32a811"
},
{
"url": "https://git.kernel.org/stable/c/3cd717359e56f82f06cbf8279b47a7d79880c6f3"
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{
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},
{
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},
{
"url": "https://git.kernel.org/stable/c/7811ba452402d58628e68faedf38745b3d485e3c"
}
],
"title": "netfilter: nf_conncount: update last_gc only when GC has been performed",
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"cveMetadata": {
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"cveId": "CVE-2026-23139",
"datePublished": "2026-02-14T15:22:24.059Z",
"dateReserved": "2026-01-13T15:37:45.972Z",
"dateUpdated": "2026-08-05T12:20:21.709Z",
"state": "PUBLISHED"
},
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"vulnerability-lookup:meta": {
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"cve": "CVE-2026-23139",
"date": "2026-09-17",
"epss": "0.0034",
"percentile": "0.27411"
},
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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"
}
}
}
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
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.
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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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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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.
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