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CVE-2026-23457 (GCVE-0-2026-23457)

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-09-08 08:46
VLAI
Title
netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()
Summary
In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp() sip_help_tcp() parses the SIP Content-Length header with simple_strtoul(), which returns unsigned long, but stores the result in unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are silently truncated before computing the SIP message boundary. For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32, causing the parser to miscalculate where the current message ends. The loop then treats trailing data in the TCP segment as a second SIP message and processes it through the SDP parser. Fix this by changing clen to unsigned long to match the return type of simple_strtoul(), and reject Content-Length values that exceed the remaining TCP payload length.
Severity
8.6 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < ed81b6a7012485acdb9c6c80735a0b7d8e5e1873 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < b75209debb9adab287b3caa982f77788c1e15027 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < 528b4509c9dfc272e2e92d811915e5211650d383 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < 75fcaee5170e7dbbee778927134ef2e9568b4659 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < 865dba58958c3a86786f89a501971ab0e3ec6ba9 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < d4f17256544cc37f6534a14a27a9dec3540c2015 (git)
Affected: f5b321bd37fbec9188feb1f721ab46a5ac0b35da , < fbce58e719a17aa215c724473fd5baaa4a8dc57c (git)
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Linux Linux Affected: 2.6.34
Unaffected: 0 , < 2.6.34 (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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            "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
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        "cveTags": [],
        "descriptions": [
          {
            "lang": "en",
            "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()\n\nsip_help_tcp() parses the SIP Content-Length header with\nsimple_strtoul(), which returns unsigned long, but stores the result in\nunsigned int clen.  On 64-bit systems, values exceeding UINT_MAX are\nsilently truncated before computing the SIP message boundary.\n\nFor example, Content-Length 4294967328 (2^32 + 32) is truncated to 32,\ncausing the parser to miscalculate where the current message ends.  The\nloop then treats trailing data in the TCP segment as a second SIP\nmessage and processes it through the SDP parser.\n\nFix this by changing clen to unsigned long to match the return type of\nsimple_strtoul(), and reject Content-Length values that exceed the\nremaining TCP payload length."
          },
          {
            "lang": "es",
            "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: nf_conntrack_sip: correcci\u00f3n de la truncaci\u00f3n u32 de Content-Length en sip_help_tcp()\n\nsip_help_tcp() analiza la cabecera SIP Content-Length con simple_strtoul(), que devuelve unsigned long, pero almacena el resultado en unsigned int clen. En sistemas de 64 bits, los valores que exceden UINT_MAX se truncan silenciosamente antes de calcular el l\u00edmite del mensaje SIP.\n\nPor ejemplo, Content-Length 4294967328 (2^32 + 32) se trunca a 32, provocando que el analizador calcule err\u00f3neamente d\u00f3nde termina el mensaje actual. El bucle entonces trata los datos restantes en el segmento TCP como un segundo mensaje SIP y lo procesa a trav\u00e9s del analizador SDP.\n\nSe corrige esto cambiando clen a unsigned long para que coincida con el tipo de retorno de simple_strtoul(), y rechazando los valores de Content-Length que exceden la longitud restante de la carga \u00fatil TCP."
          }
        ],
        "id": "CVE-2026-23457",
        "lastModified": "2026-07-24T22:10:00.140",
        "metrics": {
          "cvssMetricV31": [
            {
              "cvssData": {
                "attackComplexity": "LOW",
                "attackVector": "NETWORK",
                "availabilityImpact": "HIGH",
                "baseScore": 8.6,
                "baseSeverity": "HIGH",
                "confidentialityImpact": "LOW",
                "integrityImpact": "LOW",
                "privilegesRequired": "NONE",
                "scope": "UNCHANGED",
                "userInteraction": "NONE",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H",
                "version": "3.1"
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              "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
              "type": "Secondary"
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        "published": "2026-04-03T16:16:32.473",
        "references": [
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            "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
            "tags": [
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            "url": "https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383"
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        "weaknesses": [
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            "description": [
              {
                "lang": "en",
                "value": "NVD-CWE-noinfo"
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            ],
            "source": "nvd@nist.gov",
            "type": "Primary"
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    },
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-30T11:46:08+00:00",
      "cve": "CVE-2026-23457",
      "id": "CVE-2026-23457",
      "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_sip: fix Content-Length u32 truncation in sip_help_tcp()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-23457.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-09-11T01:35:53Z",
      "cve": "CVE-2026-23457",
      "id": "CVE-2026-23457",
      "initial_release_date": "2026-04-03T23:27:22Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "274",
      "product_status:recommended": "317",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-23457",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-23457.json",
      "version": "22"
    }
  }
}



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Tags
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.


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.