CVE-2026-23457
Full vulnerability record from the local CVENow database.
Description
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
HIGH
CVSS score
8.6
(v3.1)
Vulnerability status
Modified
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2026-04-03 16:16:32.473000
Last modified
2026-10-19 19:17:49.653000
View original CVE JSON
{
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"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-04-03T16:16:32.473",
"lastModified": "2026-10-19T19:17:49.653",
"vulnStatus": "Modified",
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"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."
},
{
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"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnetfilter: nf_conntrack_sip: corrección de la truncación 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 límite del mensaje SIP.\n\nPor ejemplo, Content-Length 4294967328 (2^32 + 32) se trunca a 32, provocando que el analizador calcule erróneamente dónde termina el mensaje actual. El bucle entonces trata los datos restantes en el segmento TCP como un segundo mensaje SIP y lo procesa a través 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 útil TCP."
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