CVE-2026-23455 (GCVE-0-2026-23455)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-08-05 12:21
VLAI
Title
netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()
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.
Severity
9.1 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 2121f5fbe88daff0f1fc5bc47d359426c74b86b0 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 65fa92f79677858b14b9e4b7275f26639afe2710 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 495e97af9e7249ee02b72bb1d0848a6efc3700f4 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < f5e4f4e4cdb75ec36802059a94195a31f193da60 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 633e8f87dad32263f6a57dccdb873f042c062111 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < 9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8 (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < b652b05d51003ac074b912684f9ec7486231717b (git)
Affected: 5e35941d990123f155b02d5663e51a24f816b6f3 , < f173d0f4c0f689173f8cdac79991043a4a89bf66 (git)
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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)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.6 , < * (custom)
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Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP Affected: V3.1.5 , < * (custom)
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Show details on NVD website
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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.\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\\n\\nnetfilter: nf_conntrack_h323: comprobaci\u00f3n de longitud cero en DecodeQ931()\\n\\nEn DecodeQ931(), la ruta de c\u00f3digo UserUserIE lee una longitud de 16 bits del paquete, luego la decrementa en 1 para omitir el byte discriminador del protocolo antes de pasarla a DecodeH323_UserInformation(). Si la longitud codificada es 0, el decremento se ajusta a -1, que luego se pasa como un valor grande al decodificador, lo que lleva a una lectura fuera de l\u00edmites.\\n\\nSe a\u00f1ade una comprobaci\u00f3n para asegurar que \u0027len\u0027 sea positivo despu\u00e9s del decremento.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/netfilter/nf_conntrack_h323_asn1.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"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\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/netfilter/nf_conntrack_h323_asn1.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"2.6.17\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"2.6.17\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.10.253\",\"lessThanOrEqual\":\"5.10.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"5.15.203\",\"lessThanOrEqual\":\"5.15.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.1.167\",\"lessThanOrEqual\":\"6.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.6.130\",\"lessThanOrEqual\":\"6.6.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.78\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.20\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.19.10\",\"lessThanOrEqual\":\"6.19.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.0\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]},{\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\",\"affectedData\":[{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.6\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.6\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.6\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.6\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.6\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]},{\"vendor\":\"Siemens\",\"product\":\"SIPLUS S7-1500 CPU 1518-4 PN/DP MFP\",\"defaultStatus\":\"unknown\",\"versions\":[{\"version\":\"V3.1.5\",\"lessThan\":\"*\",\"versionType\":\"custom\",\"status\":\"affected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H\",\"baseScore\":9.1,\"baseSeverity\":\"CRITICAL\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":5.2}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-125\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"2.6.17\",\"versionEndExcluding\":\"5.10.253\",\"matchCriteriaId\":\"CD6C2FEB-75E3-41E6-905C-667A819D083A\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.11\",\"versionEndExcluding\":\"5.15.203\",\"matchCriteriaId\":\"20DDB3E9-AABF-4107-ADB0-5362AA067045\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"5.16\",\"versionEndExcluding\":\"6.1.167\",\"matchCriteriaId\":\"2EDC6BAF-B710-4E26-B6AA-D68922EE7B43\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.2\",\"versionEndExcluding\":\"6.6.130\",\"matchCriteriaId\":\"C57BB918-DF28-46B3-94F7-144176841267\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7\",\"versionEndExcluding\":\"6.12.78\",\"matchCriteriaId\":\"28D591F5-B196-4CC9-905C-DC80F116E7A8\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.18.20\",\"matchCriteriaId\":\"E5571059-6552-48E7-9BEF-3E358C387171\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.19\",\"versionEndExcluding\":\"6.19.10\",\"matchCriteriaId\":\"96D34333-38BE-4414-9E79-6EB764329581\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*\",\"matchCriteriaId\":\"F253B622-8837-4245-BCE5-A7BF8FC76A16\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*\",\"matchCriteriaId\":\"4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*\",\"matchCriteriaId\":\"F666C8D8-6538-46D4-B318-87610DE64C34\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*\",\"matchCriteriaId\":\"02259FDA-961B-47BC-AE7F-93D7EC6E90C2\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/2121f5fbe88daff0f1fc5bc47d359426c74b86b0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/495e97af9e7249ee02b72bb1d0848a6efc3700f4\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/633e8f87dad32263f6a57dccdb873f042c062111\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/65fa92f79677858b14b9e4b7275f26639afe2710\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/9d00fe7d6d7c5b5f1065a6e042b54f2e44bd6df8\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/b652b05d51003ac074b912684f9ec7486231717b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f173d0f4c0f689173f8cdac79991043a4a89bf66\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/f5e4f4e4cdb75ec36802059a94195a31f193da60\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://cert-portal.siemens.com/productcert/html/ssa-019113.html\",\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\"},{\"url\":\"https://cert-portal.siemens.com/productcert/html/ssa-082556.html\",\"source\":\"0b142b55-0307-4c5a-b3c9-f314f3fb7c5e\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-17T16:42:08+00:00",
      "cve": "CVE-2026-23455",
      "id": "CVE-2026-23455",
      "initial_release_date": "2026-04-03T00:00:00+00:00",
      "product_status:fixed": "1778",
      "product_status:known_affected": "36",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: netfilter: nf_conntrack_h323: check for zero length in DecodeQ931()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23455.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-24T02:36:07Z",
      "cve": "CVE-2026-23455",
      "id": "CVE-2026-23455",
      "initial_release_date": "2026-04-03T23:27:25Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "222",
      "product_status:recommended": "448",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-23455",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-23455.json",
      "version": "24"
    }
  }
}



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Taxonomy of the tags.





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.


Detection rules are retrieved from Rulezet.