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CVE-2025-39946

Full vulnerability record from the local CVENow database.

Description

In the Linux kernel, the following vulnerability has been resolved: tls: make sure to abort the stream if headers are bogus Normally we wait for the socket to buffer up the whole record before we service it. If the socket has a tiny buffer, however, we read out the data sooner, to prevent connection stalls. Make sure that we abort the connection when we find out late that the record is actually invalid. Retrying the parsing is fine in itself but since we copy some more data each time before we parse we can overflow the allocated skb space. Constructing a scenario in which we're under pressure without enough data in the socket to parse the length upfront is quite hard. syzbot figured out a way to do this by serving us the header in small OOB sends, and then filling in the recvbuf with a large normal send. Make sure that tls_rx_msg_size() aborts strp, if we reach an invalid record there's really no way to recover.

Severity
MEDIUM
CVSS score
5.5 (v3.1)
Vulnerability status
Analyzed
Source identifier
416baaa9-dc9f-4396-8d5f-8c081fb06d67
Published
2025-10-04 08:15:47.747000
Last modified
2026-10-19 21:10:00.160000
View original CVE JSON 
{
  "id": "CVE-2025-39946",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "published": "2025-10-04T08:15:47.747",
  "lastModified": "2026-10-19T21:10:00.160",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntls: make sure to abort the stream if headers are bogus\n\nNormally we wait for the socket to buffer up the whole record\nbefore we service it. If the socket has a tiny buffer, however,\nwe read out the data sooner, to prevent connection stalls.\nMake sure that we abort the connection when we find out late\nthat the record is actually invalid. Retrying the parsing is\nfine in itself but since we copy some more data each time\nbefore we parse we can overflow the allocated skb space.\n\nConstructing a scenario in which we're under pressure without\nenough data in the socket to parse the length upfront is quite\nhard. syzbot figured out a way to do this by serving us the header\nin small OOB sends, and then filling in the recvbuf with a large\nnormal send.\n\nMake sure that tls_rx_msg_size() aborts strp, if we reach\nan invalid record there's really no way to recover."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\ntls: asegurarse de abortar el flujo si los encabezados son inválidos\n\nNormalmente esperamos a que el socket almacene en búfer todo el registro antes de procesarlo. Sin embargo, si el socket tiene un búfer diminuto, leemos los datos antes para evitar bloqueos de conexión. Asegurarse de que abortamos la conexión cuando descubrimos tarde que el registro es realmente inválido. Reintentar el análisis está bien en sí mismo, pero dado que copiamos más datos cada vez antes de analizar, podemos desbordar el espacio skb asignado.\n\nConstruir un escenario en el que estamos bajo presión sin suficientes datos en el socket para analizar la longitud de antemano es bastante difícil. syzbot encontró una manera de hacer esto sirviéndonos el encabezado en pequeños envíos OOB, y luego llenando el recvbuf con un envío normal grande.\n\nAsegurarse de que tls_rx_msg_size() aborta strp; si llegamos a un registro inválido, realmente no hay forma de recuperarse."
    }
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          "baseScore": 9.8,
          "baseSeverity": "CRITICAL",
          "attackVector": "NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
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          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
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          "role": "CISA Coordinator",
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  "weaknesses": [
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      "source": "[email protected]",
      "type": "Primary",
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
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