Vulnerability-Lookup

FKIE_CVE-2026-23457

Vulnerability from fkie_nvd - Published: 2026-04-03 16:16 - Updated: 2026-07-24 22:10

Severity

8.6 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

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.

References

URL	Tags
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873	Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67	https://git.kernel.org/stable/c/fbce58e719a17aa215c724473fd5baaa4a8dc57c	Patch
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e	https://cert-portal.siemens.com/productcert/html/ssa-019113.html
0b142b55-0307-4c5a-b3c9-f314f3fb7c5e	https://cert-portal.siemens.com/productcert/html/ssa-082556.html

Impacted products

Vendor	Product	Version
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	*
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0
linux	linux_kernel	7.0

JSON

To clipboard

{
  "affected": [
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      "affectedData": [
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          "product": "Linux",
          "programFiles": [
            "net/netfilter/nf_conntrack_sip.c"
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          "product": "SIMATIC S7-1500 CPU 1518-4 PN/DP MFP",
          "vendor": "Siemens",
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              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.5",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.6",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.5",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.6",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.5",
              "versionType": "custom"
            }
          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
            {
              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.6",
              "versionType": "custom"
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          ]
        },
        {
          "defaultStatus": "unknown",
          "product": "SIPLUS S7-1500 CPU 1518-4 PN/DP MFP",
          "vendor": "Siemens",
          "versions": [
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              "lessThan": "*",
              "status": "affected",
              "version": "V3.1.5",
              "versionType": "custom"
            }
          ]
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      ],
      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
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              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "E40FDCE0-F435-4862-9BEF-B0C980697894",
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              "versionStartIncluding": "2.6.34",
              "vulnerable": true
            },
            {
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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"
        },
        "exploitabilityScore": 3.9,
        "impactScore": 4.7,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-04-03T16:16:32.473",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/528b4509c9dfc272e2e92d811915e5211650d383"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/75fcaee5170e7dbbee778927134ef2e9568b4659"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/865dba58958c3a86786f89a501971ab0e3ec6ba9"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b75209debb9adab287b3caa982f77788c1e15027"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/cd1b7403ec835f8a0b3f1f7e68ac26af2cb1e42f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/d4f17256544cc37f6534a14a27a9dec3540c2015"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/ed81b6a7012485acdb9c6c80735a0b7d8e5e1873"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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    },
    {
      "source": "0b142b55-0307-4c5a-b3c9-f314f3fb7c5e",
      "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"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}

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

Vulnerability from cvelistv5 – Published: 2026-04-03 15:15 – Updated: 2026-09-08 08:46

Title

netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()

Summary

Severity

8.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H

Assigner

Linux mitre root

References

10 references

URL	Tags
https://git.kernel.org/stable/c/ed81b6a7012485acd…
https://git.kernel.org/stable/c/cd1b7403ec835f8a0…
https://git.kernel.org/stable/c/b75209debb9adab28…
https://git.kernel.org/stable/c/528b4509c9dfc272e…
https://git.kernel.org/stable/c/75fcaee5170e7dbbe…
https://git.kernel.org/stable/c/865dba58958c3a867…
https://git.kernel.org/stable/c/d4f17256544cc37f6…
https://git.kernel.org/stable/c/fbce58e719a17aa21…
https://cert-portal.siemens.com/productcert/html/…
https://cert-portal.siemens.com/productcert/html/…

Impacted products

8 products

Vendor	Product	Version
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)
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)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)

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{
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    "cna": {
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          "product": "Linux",
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              "value": "AV:N - The vulnerable parser is reached by TCP SIP packets processed by the in-kernel netfilter SIP conntrack helper on a firewall/NAT/SIP gateway. In a reasonable SIP ALG deployment, a remote peer can deliver the crafted SIP payload over the network.\nAC:L - The attacker controls the SIP TCP stream contents, including the oversized Content-Length and trailing data that is reinterpreted as another SIP/SDP message. No race or condition outside the attacker\u0027s control is required once the helper is active.\nPR:N - A remote SIP peer does not need local credentials or kernel privileges to send packets through an already configured SIP conntrack helper. Although local CAP_NET_ADMIN can configure helpers, the highest reasonable deployment is a network-facing SIP gateway where the attacker only sends traffic.\nUI:N - No victim user action is needed after the SIP helper is deployed. The crafted TCP payload is processed automatically on packet traversal.\nS:U - The affected logic is kernel netfilter conntrack/NAT state within the same security authority. This is not a VM escape, IOMMU bypass, or other cross-scope boundary break.\nC:L - The bug does not expose kernel memory, but smuggled SDP can create unintended SIP media expectations that may allow limited otherwise-blocked traffic to protected endpoints. That can expose limited traffic or service responses behind the firewall.\nI:L - The primary impact is limited integrity loss in conntrack/NAT policy state: attacker-controlled trailing bytes can be processed as a separate SIP/SDP message and create or alter expectations. This is not arbitrary kernel memory write or code execution.\nA:H - Crafted traffic can repeatedly drive incorrect SIP helper parsing, packet drops, NAT mangling, and expectation-state pollution for affected SIP flows. In a SIP gateway scenario this can deny call or media setup through the affected subsystem."
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        "dateUpdated": "2026-08-05T12:21:56.236Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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        {
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      "title": "netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-23457",
    "datePublished": "2026-04-03T15:15:38.193Z",
    "dateReserved": "2026-01-13T15:37:46.020Z",
    "dateUpdated": "2026-09-08T08:46:25.074Z",
    "state": "PUBLISHED"
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}

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.

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.

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