CVE-2026-23456 (GCVE-0-2026-23456)
Vulnerability from cvelistv5
Published
2026-04-03 15:15
Modified
2026-10-19 18:35
Severity ?
8.2 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H
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().
References
Impacted products
Vendor Product Version
Linux Linux Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
Version: 5e35941d990123f155b02d5663e51a24f816b6f3
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      "containers": "{\"adp\": [{\"affected\": [{\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.5\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.5\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.5\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.5\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.6\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.5\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}, {\"vendor\": \"Siemens\", \"product\": \"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\", \"versions\": [{\"status\": \"affected\", \"version\": \"V3.1.7\", \"lessThan\": \"*\", \"versionType\": \"custom\"}], \"defaultStatus\": \"unknown\"}], \"x_adpType\": \"supplier\", \"references\": [{\"url\": \"https://cert-portal.siemens.com/productcert/html/ssa-082556.html\"}, {\"url\": \"https://cert-portal.siemens.com/productcert/html/ssa-019113.html\"}, {\"url\": \"https://cert-portal.siemens.com/productcert/html/ssa-457936.html\"}], \"providerMetadata\": {\"orgId\": \"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\", \"shortName\": \"siemens-SADP\", \"dateUpdated\": \"2026-10-15T01:15:18.430Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-23456\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:08:25.282768Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-125\", \"description\": \"CWE-125 Out-of-bounds Read\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-10-16T15:08:25.840Z\"}}], \"cna\": {\"title\": \"netfilter: nf_conntrack_h323: fix OOB read in decode_int() CONS case\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 8.2, \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - The vulnerable parser is reached by network-delivered H.323/RAS UDP traffic when the nf_conntrack_h323 RAS helper is active on a firewall/NAT gateway. A remote peer can supply the malformed packet payload that drives DecodeRasMessage() into decode_int().\\nAC:L - The trigger is a deterministic malformed CONS integer where the 2-bit length claims 1-4 bytes that are not present. No race or attacker-external condition is required once the helper is attached to the flow.\\nPR:N - The packet decoding path has no authentication or privilege check; it runs on received network traffic before any H.323 protocol-level trust decision. Helper configuration/loading may be administrative setup, but the attacker sending the malformed packet needs no privileges on the target.\\nUI:N - Exploitation only requires sending crafted network traffic to a system processing H.323/RAS through conntrack. No victim user action is required.\\nS:U - The impact is within the kernel/network filtering security authority of the affected system. There is no guest-to-host, sandbox, or separate authority boundary crossed.\\nC:L - The bug is a bounded 1-4 byte slab out-of-bounds read from adjacent kernel memory. Because the read is strictly limited to a few bytes and not a broad arbitrary read primitive, confidentiality impact is limited.\\nI:N - The flaw is an out-of-bounds read only; it does not write beyond bounds or corrupt kernel objects. The decoded value only affects existing H.323 conntrack timeout handling.\\nA:H - A malformed unauthenticated packet can repeatedly trigger a slab out-of-bounds read in softirq packet processing, which can produce a KASAN/oops/panic on hardened or debug kernels. This is defensibly a high availability impact for affected deployments.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"a2cd54b9348e485d338b3c132338a4410c99afaf\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"c95dc674ebf01ecfb40388b6facfc89b81fed3b7\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"41b417ff73a24b2c68134992cc44c88db27f482d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"52235bf88159a1ef16434ab49e47e99c8a09ab20\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"774a434f8c9c8602a976b2536f65d0172a07f4d2\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"6bce72daeccca9aa1746e92d6c3d4784e71f2ebb\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"fb6c3596823ec5dd09c2123340330d7448f51a59\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"1e3a3593162c96e8a8de48b1e14f60c3b57fca8a\", \"versionType\": \"git\"}], \"programFiles\": [\"net/netfilter/nf_conntrack_h323_asn1.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"2.6.17\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"2.6.17\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.10.253\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.10.*\"}, {\"status\": \"unaffected\", \"version\": \"5.15.203\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.167\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.130\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12.78\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.18.20\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.18.*\"}, {\"status\": \"unaffected\", \"version\": \"6.19.10\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.19.*\"}, {\"status\": \"unaffected\", \"version\": \"7.0\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/netfilter/nf_conntrack_h323_asn1.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/a2cd54b9348e485d338b3c132338a4410c99afaf\"}, {\"url\": \"https://git.kernel.org/stable/c/c95dc674ebf01ecfb40388b6facfc89b81fed3b7\"}, {\"url\": \"https://git.kernel.org/stable/c/41b417ff73a24b2c68134992cc44c88db27f482d\"}, {\"url\": \"https://git.kernel.org/stable/c/52235bf88159a1ef16434ab49e47e99c8a09ab20\"}, {\"url\": \"https://git.kernel.org/stable/c/774a434f8c9c8602a976b2536f65d0172a07f4d2\"}, {\"url\": \"https://git.kernel.org/stable/c/6bce72daeccca9aa1746e92d6c3d4784e71f2ebb\"}, {\"url\": \"https://git.kernel.org/stable/c/fb6c3596823ec5dd09c2123340330d7448f51a59\"}, {\"url\": \"https://git.kernel.org/stable/c/1e3a3593162c96e8a8de48b1e14f60c3b57fca8a\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"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().\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.10.253\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.203\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.167\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.130\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.78\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.18.20\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.19.10\", \"versionStartIncluding\": \"2.6.17\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"7.0\", \"versionStartIncluding\": \"2.6.17\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T12:21:55.155Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-23456\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T18:35:44.721Z\", \"dateReserved\": \"2026-01-13T15:37:46.020Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-04-03T15:15:37.534Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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