CVE-2026-23455 (GCVE-0-2026-23455)
Vulnerability from cvelistv5
Published
2026-04-03 15:15
Modified
2026-10-19 18:35
Severity ?
9.1 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931() In DecodeQ931(), the UserUserIE code path reads a 16-bit length from the packet, then decrements it by 1 to skip the protocol discriminator byte before passing it to DecodeH323_UserInformation(). If the encoded length is 0, the decrement wraps to -1, which is then passed as a large value to the decoder, leading to an out-of-bounds read. Add a check to ensure len is positive after the decrement.
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\": \"2026-10-15T01:15:16.674Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-23455\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"yes\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-10-16T15:08:22.829066Z\"}}}], \"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\": \"2026-10-16T15:08:23.407Z\"}}], \"cna\": {\"title\": \"netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 9.1, \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - The vulnerable H.323/Q.931 conntrack helper parses TCP network traffic, typically on H.323 call signaling flows through a firewall/NAT gateway. A remote peer can supply the malformed TPKT/Q.931 packet once the helper is active for that flow.\\nAC:L - The trigger is a deterministic zero-length UserUserIE in an otherwise reachable Q.931 message; there is no race or condition outside the attacker\u0027s control. TCP establishment and helper deployment are normal operating conditions for the affected subsystem.\\nPR:N - The attacker only needs to send network traffic to or through a system using the H.323 conntrack helper. No authentication or local privileges are required on the target system.\\nUI:N - Exploitation occurs during automatic packet processing in the kernel netfilter path. No victim user action is required.\\nS:U - The vulnerable component and impacted resources are within the same kernel/network filtering security authority. This is not a VM escape, IOMMU bypass, or cross-sandbox boundary violation.\\nC:H - The integer underflow turns a zero encoded length into a huge decoder length, causing an out-of-bounds read beyond the packet buffer. Under the kernel guidance, an unbounded out-of-bounds read is High confidentiality impact.\\nI:N - The bug is a read-side parser bounds failure and does not provide an out-of-bounds write, arbitrary write primitive, or direct control-flow corruption. Any resulting malformed conntrack processing is not enough to justify kernel data integrity compromise.\\nA:H - The out-of-bounds read can fault or otherwise destabilize kernel packet processing, producing an oops/panic or repeated denial of service. A remote attacker can resend malformed packets to retrigger it.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"2121f5fbe88daff0f1fc5bc47d359426c74b86b0\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"65fa92f79677858b14b9e4b7275f26639afe2710\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"495e97af9e7249ee02b72bb1d0848a6efc3700f4\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"f5e4f4e4cdb75ec36802059a94195a31f193da60\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"633e8f87dad32263f6a57dccdb873f042c062111\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"b652b05d51003ac074b912684f9ec7486231717b\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"5e35941d990123f155b02d5663e51a24f816b6f3\", \"lessThan\": \"f173d0f4c0f689173f8cdac79991043a4a89bf66\", \"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/2121f5fbe88daff0f1fc5bc47d359426c74b86b0\"}, {\"url\": \"https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710\"}, {\"url\": \"https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4\"}, {\"url\": \"https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60\"}, {\"url\": \"https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111\"}, {\"url\": \"https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8\"}, {\"url\": \"https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b\"}, {\"url\": \"https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66\"}], \"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: check for zero length in DecodeQ931()\\n\\nIn DecodeQ931(), the UserUserIE code path reads a 16-bit length from\\nthe packet, then decrements it by 1 to skip the protocol discriminator\\nbyte before passing it to DecodeH323_UserInformation(). If the encoded\\nlength is 0, the decrement wraps to -1, which is then passed as a\\nlarge value to the decoder, leading to an out-of-bounds read.\\n\\nAdd a check to ensure len is positive after the decrement.\"}], \"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\": \"2026-08-05T12:21:54.080Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-23455\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-19T18:35:44.554Z\", \"dateReserved\": \"2026-01-13T15:37:46.020Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2026-04-03T15:15:36.869Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
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