CVE-2026-23456 (GCVE-0-2026-23456)
Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-09-08 08:46
VLAI
EPSS
VEX
Title
netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
Summary
In the Linux kernel, the following vulnerability has been resolved:
netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case
In decode_int(), the CONS case calls get_bits(bs, 2) to read a length
value, then calls get_uint(bs, len) without checking that len bytes
remain in the buffer. The existing boundary check only validates the
2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint()
reads. This allows a malformed H.323/RAS packet to cause a 1-4 byte
slab-out-of-bounds read.
Add a boundary check for len bytes after get_bits() and before
get_uint().
Severity
8.2 (High)
Assigner
References
10 references
Impacted products
8 products
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Linux | Linux |
Affected:
5e35941d990123f155b02d5663e51a24f816b6f3 , < a2cd54b9348e485d338b3c132338a4410c99afaf
(git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < c95dc674ebf01ecfb40388b6facfc89b81fed3b7 (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 41b417ff73a24b2c68134992cc44c88db27f482d (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 52235bf88159a1ef16434ab49e47e99c8a09ab20 (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 774a434f8c9c8602a976b2536f65d0172a07f4d2 (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 6bce72daeccca9aa1746e92d6c3d4784e71f2ebb (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < fb6c3596823ec5dd09c2123340330d7448f51a59 (git) Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 1e3a3593162c96e8a8de48b1e14f60c3b57fca8a (git) |
guessed | |
| Linux | Linux |
Affected:
2.6.17
Unaffected: 0 , < 2.6.17 (semver) Unaffected: 5.10.253 , ≤ 5.10.* (semver) Unaffected: 5.15.203 , ≤ 5.15.* (semver) Unaffected: 6.1.167 , ≤ 6.1.* (semver) Unaffected: 6.6.130 , ≤ 6.6.* (semver) Unaffected: 6.12.78 , ≤ 6.12.* (semver) Unaffected: 6.18.20 , ≤ 6.18.* (semver) Unaffected: 6.19.10 , ≤ 6.19.* (semver) Unaffected: 7.0 , ≤ * (original_commit_for_fix) |
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.6 , < *
(custom)
|
guessed | |
| Siemens | SIPLUS S7-1500 CPU 1518-4 PN/DP MFP |
Affected:
V3.1.5 , < *
(custom)
|
guessed |
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case\n\nIn decode_int(), the CONS case calls get_bits(bs, 2) to read a length\nvalue, then calls get_uint(bs, len) without checking that len bytes\nremain in the buffer. The existing boundary check only validates the\n2 bits for get_bits(), not the subsequent 1-4 bytes that get_uint()\nreads. This allows a malformed H.323/RAS packet to cause a 1-4 byte\nslab-out-of-bounds read.\n\nAdd a boundary check for len bytes after get_bits() and before\nget_uint()."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: nf_conntrack_h323: correcci\u00f3n de lectura fuera de l\u00edmites (OOB) en el caso CONS de decode_int()\n\nEn decode_int(), el caso CONS llama a get_bits(bs, 2) para leer un valor de longitud, luego llama a get_uint(bs, len) sin comprobar que len bytes permanezcan en el b\u00fafer. La comprobaci\u00f3n de l\u00edmites existente solo valida los 2 bits para get_bits(), no los 1-4 bytes subsiguientes que lee get_uint(). Esto permite que un paquete H.323/RAS malformado cause una lectura fuera de l\u00edmites de slab de 1-4 bytes.\n\nA\u00f1adir una comprobaci\u00f3n de l\u00edmites para len bytes despu\u00e9s de get_bits() y antes de get_uint()."
}
],
"id": "CVE-2026-23456",
"lastModified": "2026-07-24T22:10:00.140",
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"attackVector": "NETWORK",
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"baseScore": 8.2,
"baseSeverity": "HIGH",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H",
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"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
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"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-125"
}
],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
},
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"aggregate_severity": "Moderate",
"current_release_date": "2026-06-30T11:46:06+00:00",
"cve": "CVE-2026-23456",
"id": "CVE-2026-23456",
"initial_release_date": "2026-04-03T00:00:00+00:00",
"product_status:known_affected": "274",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "kernel: netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23456.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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