CVE-2026-52986

Estado: ModificadaCrítica (9.8)—

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_sip: don't use simple_strtoul

Replace unsafe port parsing in epaddr_len(), ct_sip_parse_header_uri(), and ct_sip_parse_request() with a new sip_parse_port() helper that validates each digit against the buffer limit, eliminating the use of simple_strtoul() which assumes NUL-terminated strings.

The previous code dereferenced pointers without bounds checks after sip_parse_addr() and relied on simple_strtoul() on non-NUL-terminated skb data. A port that reaches the buffer limit without a trailing character is also rejected as malformed.

Leer descripción completaMostrar menos

Also get rid of all simple_strtoul() usage in conntrack, prefer a stricter version instead. There are intentional changes:

Based on an earlier patch from Jenny Guanni Qu <qguanni@gmail.com>.

Detalles técnicos trazas, registros y código del informe original

- Bail out if number is > UINT_MAX and indicate a failure, same for
  too long sequences.
  While we do accept 05535 as port 5535, we will not accept e.g.
  'sip:10.0.0.1:005060'.  While its syntactically valid under RFC 3261,
  we should restrict this to not waste cycles when presented with
  malformed packets with 64k '0' characters.

- Force base 10 in ct_sip_parse_numerical_param(). This is used to fetch
  'expire=' and 'rports='; both are expected to use base-10.

- In nf_nat_sip.c, only accept the parsed value if its within the 1k-64k
  range.

- epaddr_len now returns 0 if the port is invalid, as it already does
  for invalid ip addresses.  This is intentional. nf_conntrack_sip
  performs lots of guesswork to find the right parts of the message
  to parse.  Being stricter could break existing setups.
  Connection tracking helpers are designed to allow traffic to
  pass, not to block it.

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 9.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.62%
Percentil entre todas las CVEs puntuadas: 48
Fecha de la puntuación: 6/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1190 Exploit Public-Facing Applicationinitial access85 %
Impacto principalT1059 Command and Scripting Interpreterexecution80 %
Impacto secundarioT1068 Exploitation for Privilege Escalationprivilege escalation70 %

Vulnerabilidad crítica de parsing en netfilter (AV:N, sin autenticación) permite ejecución de código remoto explotando desbordamiento de buffer en manipulación de puertos SIP sin validación de límites; acceso a kernel implica escalada de privilegios.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Privileged Account Management Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software Vulnerability Scanning

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

CWE-476

Referencias

JSON original (NVD)

Mostrar

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